Leather at least - the Warlock can be specced to do a fair bit of melee damage (especially with the new and improved Firestone). Skinning your victims fits well with the whole Necro / Dark Arts side of the Warlock.
I'm probably not best placed to say what needs fixing at the moment - still only lvl25. Going from what I've read on the forums (taking most of it with liberal amounts of salt...)
I think getting all of our skills to work as described would be a good start.
Some sort of root spell would be nice too. Perhaps some sort of bear-hug from the voidwalker? Make Fear insta-cast please :O)
Someone suggested that we should be able to take on a Demonic Form at higher levels. That'd be a bit funky :O)
Shards are a pain, but I don't really see a better way of doing it. Removing the need for shards would make us a bit overpowered or require far too great a change to the class.
I don't understand why the "paranoia bug" is a bug - increasing stealth detection is a pish skill, having it generate aggro at the same time isn't necessarily a bad thing. If anything they should consider reducing the ability to spam this skill, but leave the aggro creation in.