For the most part, ignoring the military specifics, the political debate seems to hinge on whether the "no-fly" zone has morphed into something more, or at least something else. There are opinions all over the map about that, so let's look at the actual language of the UN resolution as a starting point.
UN resolution 1973 says this:
Demanding an immediate ceasefire in Libya, including an end to the current attacks against civilians, which it said might constitute “crimes against humanity”, the Security Council this evening imposed a ban on all flights in the country’s airspace — a no-fly zone — and tightened sanctions on the Qadhafi regime and its supporters.
Adopting resolution 1973 (2011) by a vote of 10 in favour to none against, with 5 abstentions (Brazil, China, Germany, India, Russian Federation), the Council authorized Member States, acting nationally or through regional organizations or arrangements, to take all necessary measures to protect civilians under threat of attack in the country, including Benghazi, while excluding a foreign occupation force of any form on any part of Libyan territory — requesting them to immediately inform the Secretary-General of such measures.
The first paragraph speaks specifically of the "no-fly" zone. That's pretty clear. The second paragraph adds some additional ideas, specifically ...take all necessary measures to protect civilians under threat of attack in the country, including Benghazi, while excluding a foreign occupation force of any form on any part of Libyan territory
Now, that language suggests additional things. Depending upon exactly how we read that, "all necessary measures to protect civilians" could mean almost anything where somebody perceives a threat. Clearly a military unit, or even a squad of policemen, walking down the street shooting at people would likely qualify, especially if they are acting under orders. To me, it seems to suggest that even if they weren't acting under orders.
Of course, like all things political, there are always nuances and hidden concepts. In this case, since a "foreign occupation force of any form" is specifically precluded, that means outsiders can only change things through the use of air power. That might include planes, conceivably helicopters, unmanned guided missiles, and perhaps drones.
Those things might not have been intended by some who supported the resolution, but to me the language, at least in the English version, opens the door. I should caution that sometimes these things don't translate well, so the "intent" in some other languages might seem very different. As an aside, the original Four Power Agreement to govern the city of Berlin at the end of WWII had this very problem, and it caused no end of problems over and above the issues between Russia and the western allies.
Ultimately, no matter how you parse those words, the situation becomes obvious. The resolution places the UN, or at least its member states, in the position of taking sides in what is essentially a civil war. The exact nature of the sides is unclear. On one side you have the current government, which I believe can best be described as oppressive. The threat to go "house to house" cleansing the nation of rebels was clearly a "threat" in any language.
On the other side, however, we have the "rebels." They claim to seek freedom from oppression, which is undoubtedly true. What is less clear is exactly what they have in mind when and if they succeed in doing that. Trading one oppressive regime for another, with only the haves and have-nots trading places, isn't a good long-term solution.
Ultimately, we all need to acknowledge one eternal truth: Democracy isn't easy!
In a nation with no democratic history, the people are faced with a myriad of new choices and responsibilities, often with no experience or expertise to guide them. Old issues, such as tribalism, don't suddenly go away. The disparity between the rich and poor remains. In the case of Libya, how does the country share the revenue from their oil, which represents, according to some figures, nearly 90% of their export income?
At this point, the ultimate outcome...which side wins...is still in doubt. Personally I have few doubts what Libya would look like if the current regime manages to stay in power. It's not a pretty picture.
On the other hand, I have no idea what a new government might look like. Neither does anyone else. For those on the outside who desire "Democracy" there is a risk, for even if a pure democracy was established, the people of Libya, for whom we are supposedly doing all of this, might just select a government that "we don't like." Democracy is like that. Democracy is messy, noisy, and confused. As we have seen in the US, even with years of experience, it's still hard to make function well, and elections often mean abrupt about-faces.
At this point, the world appears to have collectively chosen sides, and given the current regime's statements, that's not terribly surprising. There is a suspicion that Oil plays a big part in all of this, and that's likely true to some degree. No one can say how much. In the end, all anyone can do is support the people as they search for "something better" and hope they succeed in finding it. Hopefully, "something better" will be better for every Libyan.