MySpace was destroyed by cultural problems. The technology wasn't at fault. If it was populated with HN-types, we'd see clean typography and beautiful blogs - not the epileptic-fit-causing profile pages that caused everyone to migrate to Facebook.
Culture is the difference between MySpace and Tumblr.
Building a community is everything. That's my thesis, at least.
Myspace could have survived myriad cultural problems on the strength of their once unparalleled social graph if they could have kept pace with Facebook's technology. Facebook had many things right - the news feed, valid identities, speed - that would have required Myspace to essentially start from scratch to even emulate. Myspace tried, but couldn't pull it off.
So my argument is that Facebook has room to experiment in areas where tastes may differ (i.e. culture) as long as they have great technology and an adaptable design. If the timeline/ticker turns out to be completely overwhelming and they see usage drop, Zuckerberg could practically issue an apology, flip a switch and basically turn Facebook back to yesterday's Facebook by Monday. As their experiences with failure (Beacon) and success (the news feed!) have shown, there's way more upside than downside.
Twitter seems no worse for it, and a failure to cater to elitists wasn't MySpace's problem either. MySpace, AOL, Yahoo, HP -- their problems are cultural, but not their users' culture, their managements'.
Very, very true.
I would even expand on this. Problems people encounter online can be divided into technical, social (involving groups) and interpersonal. Problems from one category cannot be effectively solved via methods from another. Attempting to do so inevitably results in many undesirable side-effects.