And if we didn't have the Lib Dems in government we would have....?
(a) A minority government made up entirely of the Conservative Party, which would be worse (and which would possibly have deliberately self-destructed already in order to call a general election and try to win it before all the cuts came in).
(b) A Rainbow Coalition made up of Labour and various other parties (Labour-LibDem alone would not have been sufficient numbers). Pulling in different directions, probably chaos. It would have survived thus far, maybe not implementing as many cuts as the Coalition, but aware that it had to something, and do it soon. The frustrations of the clash of idealism and Realpolitik would soon have seen it flounder.
(c) A minority Labour government with Gordon Brown still in charge? Never going to be an option - would struggle to get anything passed and would inevitably be seen as a "lame duck".
All three of those possibilities above would have resulted in another General Election within a year of the last - sounds great to some people, until you realise the parties can't afford it and don't have the stomach for it.
Given the result as it was (and not as you would have liked it to be), what other realistic options were there?