Why does a set almost always has chest / shoulder / head?

Barring few exceptions, sets have chest / shoulder / head components: this for both epic as well as legendary sets.

Why not come up with sets that have boots / legs / belt, legs / arms / ring, or other unusual combinations?

Short answer is for balancing.

+1 to all skills in (class name) is a stat only available in belts, heads and weapons and amulets and a certain comic relief torso.
Having a set that doesn’t use headgear means you can get an extra boost in +1 to all skills to chosen class. etc
Not exactly game-breaking per se but I feel the devs want a limit to how many free points is achievable in an end-game build and this is one such countermeasure.

Then don’t use it in the set for the mentioned slots unless it’s for set partial / full completion? That way, it would provide the same + skills in (class name) while providing something else for partial / full set completion bonus: with so much stats to go around, i’m sure the devs could think of something to include in that department. For example, flat life stat (600+).

Nature’s avenger doesn’t have headgear, and it’s pretty middling as far as sets go. It also feeds into the popularity of MI pants/boots, since I don’t think a single item set uses those slots.

Three epic sets use the pants slot. One epic and two legendary sets use the boots slot. There are no green MIs for the boots slot. Stoneplate Greaves is actually a craftable magic item.

Out of how many sets total? That’s just a tad bit more then “a drop in the ocean”.

A lot of builds use stoneplate boots as their choice for boots in the builds. Unless one is quite lucky, it takes a heck of a lot of tries to get good boots. Same is true for Solael-Sect pants because, more likely then not, one will need a heck of a lot of runs to get decent ones.

Perhaps if there were more sets using pants / boots / something else (/ other something else) (not chest / helm / shoulders or, @ most, one of these as these slots are the most common in sets), these green items were less necessary?

If there were more sets that used the pants and boots slot, you’ll see more people using green rings, or putting greens in other slots. The game sets do not have enough defensive stats, so people use green gear to compensate. Currently it’s been made easier on us, by making boots and pants slot hardly ever used in sets, so we use those slots to fix up the characters weakness. Rings and medals are also common slots to add some green gear to fix up defenses.

But if you could use 2 sets simultaneously because one uses … say … helm / chest / weapon / shoulders while the other uses … say … pants / boots / medal, perhaps the bonuses from both sets could help fix those issues you mention.

It’s not mandatory to use the full set(s) either. My S&B blademaster doesn’t use Warborn weapon, even though it’s part of the set (for obvious reasons, ofc). We could still use a green piece instead of a set piece if necessary.

Set pieces tend to be more offensively minded and at the least, always leave resists in tatters. Mixing 2 sets is highly unlikely to work due to that. Though I guess it might be interesting to try. I doubt many would fit unless the dev’s actually tried to make the work together.

Like i said, it doesn’t have to be both whole sets: but 2 / 3 / 4 pieces of each (depending on total amount of pieces the sets have, ofc).

Currently most sets have an offensive orientation: perhaps sets like those i suggest could have a more defensive orientation? Be it in the form of extra life / res / DA / secondary res / something else that doesn’t come to mind right now.

All I am getting at is this would likely be work the dev’s put in, and we never use due to the inherent issues with set pieces not covering your resists and DA needs very well to begin with.

The chest, helm and shoulders are the most visible parts of the character. So from an art perspective it makes sense to focus on them, when making unique models for set items.

Many builds use Sonehide Solael-Sect Legguards Nature’s Bounty / Kings: this item is clearly defensive in nature.

What if we had set(s) that could have this type of defensive nature + the bonuses from more than 1 set pieces? These sets should have gear pieces that most other sets don’t have.

You get (on average) 26% pierce, 40% poison, 26 elemental, 30 aether and 76 bleeding resistance from just the Solael-Sect pants, not to mention 500 life and HP regen. If pant’s from set(s) gave similar bonuses + extra ones from other pieces of the same set, wouldn’t that be worth it?

After all, it’s a lot harder to get these pants then it is to get set pieces because you can trade for the set pieces but you’d most likely not be able to do so with pant’s like these. Same goes for every other good MI really.

Unless they design the sets to cover specific resists, you are always going to have to have a few pieces of gear you have to swap in to balance them out. At this point, I just don’t see how they’d ever do that, as they’d have to redesign all the stats on the gear, and probably make generic stats almost every set has to make it work.

I just don’t see a need to change it up at this point. And unless they redesigned all sets to cover specific resists and DA needs, I would never do this anyway, and I doubt many would. The game has way too many resists to worry about. That flaw makes it so we need non set slots to fix their problems.

Imagine a set with 4 pieces that has pants, boots, ring and relic.

1 - Pants - +20 elemental res, +25 aether res, 600 life, +20 HPR/s, +60 OA
2 - Boots - +20 elemental res, +25 chaos res, +10 MR/s, +10 movement, +60 DA
3 - Ring - +12 to +15 (dmg type) dmg, +25 vitality res, +25 chaos res, 450 life, +75 OA
4 - Relic - +20 vitality res, 500 life, +4 crit, +60 DA

The above is on top of +X% (dmg type) dmg, +Y% (dmg type) dmg, +Z% (dmg type) dmg on some or all of the pieces.

Then you also get set bonuses for completion:

2 pieces - +500 life
3 pieces - +10 to all primary resists
Full set - +80 OA, +60 DA, +4 crit

The above example is possibly a bit overpowered, but you get the picture, right? The idea is that good MIs such as Sonehide Solael-Sect Legguards of Nature’s Bounty / Kings or Cutthroat’s Gollus’ Ring of the Basilisk (depending on the build, ofc) are still the best in slot but have a much more accessible alternative.

It can work, but they’d have to redesign every set there is to fit that model. I highly doubt they’ll ever do that, plus it makes the game rather boring in the sense that much of the stats are pretty much set in stone on every set.

It’s just not going to happen at this point.

Redesign? I’m talking about introducing other sets besides the current existing ones: no need to touch the existing ones, and this goes for epic as well as legendary sets. Introduce like two or three epic / legendary sets.

The example i gave in my previous reply is probably a bit much but the general idea is to have the MIs still be the best in slot but have decent alternatives for those that are trying but still haven’t been able to get those great MIs.

If your numbers were to supposed to represent existing sets, I’m sorry, but that does not fix the problems I stated prior. Existing gear doesn’t have enough resists or stats to exist without heavy use of specific gear to fix up your stats, and this whole introduction would be pointless. Every character has to pick a lot of specialty items for every build to fix up stats that the sets miss. Trying to make your whole getup a set, will either dumb down the gearing process (e.i. there will be multiple sets that just fit, with no other work needed), or they just won’t be usable because they don’t work.