As the title states. Because why not? I know FG is coming and everyone will be all about SR but Crucible is still the best place for the quick few crafts and tweaks. But with no dummies you gotta quit and go to main game to see your stats with Lethal Assault or Savagery.
I had the same thought when testing some stuff with items I had on my stash character. I wanted to test some skills etc and made a skill that reduces all requirements just to wear some items and check their skills. Then I realized I’ll have to go to the main campaign to do that.
As someone who regularly switches back between Crucible and Campaign just for the dummies, this would be a huge plus.
So, an obvious +1.
Hey, you don’t play crucible!
It’s not about playing it. It’s the place where everything is: smith for components, inventor, vendor for pots, stash, skill points. Just a dummy is missing. One would be enough. Next to the inventor.
I only add/take items from Crucible because my stash characters are level 1 without any quests done. 
I could simply replace their world files, now that I think about it… That’s a good idea, dude, thanks for that advice!
In FG you can just buy them ultimate access and BOOM full bags mule!
So you pay for that service? xD