I personally don't begrudge anyone their affection for MySpace (or any other outdated or inefficient technology) — you're right that for some people that's what's comfortable, and that's totally fine with me. To each their own, and you're right too that as artists we have to be aware (and respectful) of the avenues fans take to find us.
But when it comes to my own experience, it's really just a matter of impracticality, both as an artist and a fan. Personally, I *want* to listen to all the bands / artists who request my friendship. But to do that nowadays (i.e., the problem seems to have gotten worse as the site grows) — given the number of requests I get, and given the bugginess of the site — I would probably have to set aside an entire "MySpace day," once a week. And I wouldn't even mind doing that, except that half of that day would be spent waiting for the music to start.
I still do my best to check in on MySpace regularly — but nowadays it's usually while I'm in "multitasking" mode.