"It's all about the oil = money."
That's kind of where it all falls down actually.... We already had the oil.
We've had access to Libyan oil since Gadaffi officially dropped his WMD programs. The US normalised relations and stopped its sanctions back in 2006.
Yes it left a psychotic nutter in charge of the country, but that doesn't usually bother us, the oil fields were opened up and we had long term (25 year) contracts to exploit them.
And we've now gone and put all that at risk and interrupted the oil flow for an indeterminate period of time. We have no guarantees that the new Government will respect all the contracts of the old one and we might end up with a Government that is far more hostile to the west than the current one.
So it's very odd, nice and secure oil has been put at risk.
I don't believe for one moment that that was done for purely moral reasons, we're quite happy to accept mad tyrants if we get the oil, but it's nowhere near as simple as saying "we did it for the oil".