Yeah, having all of your messaging in one place is amazing. Especially since they support a decent long tail of DM services as well.
My IM situation is only currently tolerable because all of my frequent contacts are either via WhatSapp or twitter DM.
Even having the handful you do would be enough to make -me- want to consolidate.
(this is not at all meant to be an argument that -you- should want it, but I think is at least a good case that there will be people out there in your -situation- that will)