The changes you’re referring to didn’t affect Skeletons much at all; they shifted some of the Vitality damage from Raise Skeletons to Will of the Crypt. The change was necessary because Raise Skeletons initially had huge Vitality damage per pet for a skill that was meant to have 10+ pets. In fact, by late AoM, Skeleton Cabalists had some of the best-performing Crucible builds, but that was more due to how good the synergy was between Raise Skeletons and Occultist’s Raven.
FG was not nice to Skeletons: the synergy with Raven was cut by forcing a whole set to summon 2 birds, and some of the FG bosses - especially Kaisan and Korvaak - are specifically brutal for builds that don’t have all pet resistances capped. Compounding the problem is that Master of Death is not particularly a good Exclusive, especially as the gearing is diverse enough that you can cover DA and pet OA without it. It doesn’t help that items that give bonuses to essential skills like Will of the Crypt don’t cover the pet resistances you need; not to mention the meme items like Elemental Skeleton Spellbinders with no RR that I pointed to in the OP.