Yeah, Lain jumped out to me as a questionable inclusion in that list as well. It has hikikomori themes, though I wouldn't have thought of it that way before, but no major characters are hikikomori. OTOH Tatami Galaxy makes sense to me, given the analysis paralysis sort of thing going on in that, even if it isn't always directly about hikikomori. Rozen Maiden is really the only straightforward choice there.