Of course vanilla FO4 wont let you apply Ballistic Weave to the Vault Suit. But do we think this is a BUG or by design? There are plenty of mods to let you do this. Like this one:

http://www.nexusmods.com/fallout4/mods/4052/?

I like to try to keep things fairly lore friendly and balanced.

Also...the list of clothes that get the weave seems pretty random...some hat but not all hats get it. This looks to me like mistakes when someone was filling out tables.

What do you all think?

Vault Suit has it's own set of mods, and honestly I don't think any base-layer apparel should get Ballistic Weave. Or hats. It's definitely inconsistent at this point - at some point I really just want to go through all of the apparel records and clean it up a bit, as well as checking every clothing item to see if they clip with every armor type (some of them, like the T-Shirt & Slacks, really don't look like they would) and making them base layer if they don't.