In this morning's phone-in, it seemed to be lumped in with not using bells as unnecessarily surprising to people walking on/near cycle tracks. I think when one was asked whether they said anything, their reply was something like "what can you say? By the time you do, they've gone" so I don't think I'd take never hearing a complaint on the street as proof no-one cares. Loads of people seem so scared about being the victim of a Kenneth-Noye-style road rage attack if they criticise another road user.
I don't much care about it either way personally, but it seems to really upset some people and I have the lights anyway (the batteries last >10 hours, or I often use dynamos) so I don't see much reason not to light up.