Meh. The way I see it, this whole debacle is a prime example of why it isn't a good idea to expect administrative divisions to work as national ones. Modern Ukraine is what the Soviet government decided should be administered from Kiev. It was never meant to be a national border, and big surprise, it turns it it isn't really working out as one. Something similar also happened with Russia's other former soviet neighbor that tried to get closer ties with the West: Georgia*.
This is pretty much why I have trouble caring about the whole situation. The existing borders were never meant to be borders when they were drawn up. I'm not on Russia's side, but I'm certainly not behind the West's "maintain the status quo at all costs" position either. Saying that all this is only Russian imperialism is like saying Russia is only involved to protect people.
TBH, a proper, internationally-supervised referendum on secession for each region would probably be the way to go, but I don't think either Ukraine or Russia want to take the chance that it won't go their way. And the separatists probably wouldn't either.
* There's also the Baltic states, but they're a rather special case.