I couldn't do it, but I find tons of mannequins while questing. I would love to be able to set them up in my base's display room with various outfits or armor sets for display!

Anyone else think this is something they'd want? Maybe also include option to add a weapon on the mannequin?

Yeah... One of those odd things.

Skyrim had some house-related features in it (even vanilla Skyrim.) That included mannequins and trophy places for your weapons and such.

Fallout already has mannequins in the world, as an object that you can just find anywhere - but now that Fallout 4 has this big settlement crafting function you can't do the same thing with those mannequins that you could in Skyrim. Hopefully they expand upon these elements a bit in the future.