Okay, you deserve a better explanation that one-liners.
It's not often you get a truly just war, but anything that involves greasing Ghaddffi (the world's second-foremost cartoon dictator) and ending that regime comes pretty damned close. This isn't the abortive uprising in Iraq in 1991/92, nor is it the "Northern Alliance" of Afghan memory, or the Iran uprisings. The rebels were out there doing the real heavy lifting all on their own, bleeding and dying without anybody having promised them help or showing up with a train of M1 Abrams for them to hide behind.
The rebel leadership has taken great pains to demonstrate that they're not a bunch of extremist nutjobs and are doing a surprisingly good job of putting together a rough-and-ready provisional government. And they managed to impress Biden, Hilary, and half the EU in the process. Best estimates show that a clear majority of the population of the country is rebel or has strong rebel sympathies. In fact the core of the rebel army is comprised of defecting regiments from the regular army. They're more than just a one-hit wonder too. After the recent setbacks, they dug in and showed resilience and resourcefulness in a long fighting retreat.
The Rebels almost managed to toss Ghadaffi out on their own, pushing him almost to a small area around Tripoli, until regime armour, artillery, and air assets started getting into play. They easily outnumber the regime forces in manpower (even more so when morale is good - some of the non-soldiers are hedging their bets by fleeing when things get back. But they're not trained soldiers, so I can't lay blame there). But the effects of heavy artillery and armour were simply too much.
Various rebel mouthpieces have been saying that a Ghaddafi victory will mean genocide. It's easy to be cynically skeptical of this, especially considering a biased source, but don't forget, who we're talking about here. Momar Ghaddafi. Even leaving his past aside, he's been damn well doing his best in the past two weeks to show that genocide is something he's relishing very much. The regime has been about as indiscriminate in it's killing as can be.
Sure you can say something nasty like "They were too good for our help, but when the going got rough they came whining for the US to step in". The rebels originally asked the UN for a no-fly zone, not for intervention. Basically the rebel view is partially a fear of foreign dominance, but it's also an old-fashioned homegrown pride issue. They want to do this themselves. I mean, that's something truly precious, something you almost never see anymore.
They want a no-fly zone because they're not afraid of being outgunned by tanks or artillery - they can fight those, though it's difficult (and if they can get some heavier weapons they can balance that out very quickly). But they couldn't counter air power and even if someone gave them planes, they wouldn't have an instant air force to fight with - that takes time they don't have. Forcing both sides to stay on the ground would go a long way towards evening things up and to boosting rebel morale.
Those men have more guts than most. Up until yesterday, I was saying to anyone who cared to listed that if I had my way, NATO would be their personal airforce and I'd be dumping planeloads of easy weapons and supplies for 'em like there was no tomorrow. They've got the fight in 'em, and they've got the numbers. Just give them the tools. I thought that would probably a bit too much for the realpolitik lot, but today has been a day for grand surprises.
The Afghans hate everybody,
The Iraqis were invaded based on trumped-up imperialist nonsense and everyone knew it,
These guys were out taking artillery in the face for weeks before they started asking for help.