EDIT: since I'm getting downvoted because some of you don't agree:
There's like 140M active Twitter users (as of March 2012) and like, 30 clients (guesstimating). If I assume there's like 1M developers on Twitter (which I don't think it is), this feature is still useful to less than 1% of their user base. Not exactly a "must have" feature IMHO.