I think you're being too cynical here.
Can you honestly see Labour, the Labour-supporting press, the student protests, etc etc, failing to hammer the Lib Dems a jot less for propping up a purely Conservative Government?
It's hardly just the groups you've named hammering the Lib Dems, though. Not just the Labour-supporting fraction, most of the press has hammered the LDs for abandoning the moral high-ground they've so studiously claimed for so long. And the hardest hammering has come from their own voters.
And yes, there would be a lot less hammering, from practically everyone. Giving confidence and supply to a minority government gives the LDs complete freedom to pick which things they support and which things they oppose. There aren't going to be any student protests, for instance, because a minority Conservative government just wouldn't have the votes to raise tuition fees (it isn't even going to take the risk of alienating so many middle-class parents when it could be brought down at any moment by a simple censure motion). The LDs would take each issue on its merit - and the fact that they're doing that means the Tories would have to make a more convincing case and more compromises to win support, which mean some of the things that are sharply unpopular in OTL would be more widely tolerated.
The Tories, equally, will have no real reason to hold back from attacking the party, and the Conservative press will be baying for blood, in a way that even now I think is somewhat dampened by the fact that the Liberal Democrats are in Government. The Tories will be able to say at the autumn 2010 or spring 2011 election, quite reasonably, that the Liberal Democrats have no interest in power with anyone other than Labour, which will certainly not help them in the SW.
If they're a minority government being propped-up by the LDs, the Tories certainly aren't going to say any of that very loudly. From the LD perspective, the same fundamental argument applies to confidence as to coalition ("we're being responsible, ensuring government goes on") but they don't get trapped into supporting legislation they don't want to support. Now that's not without consequence. Yes, the Tories can say "if only we had a majority, or a coalition supporting our legislation, this would all be going much better", and some people would believe them; and Labour can win back some of the disaffected Labour voters who switched to the LDs simply because the LDs are supporting a brand that is toxic with those voters (but nowhere near as many as they are going to in OTL). So the LDs wouldn't be doing quite as well in the polls as they did in 2010; but they'd be doing much, much better than they are now - the LDs would not have become so toxic, especially not with so many people who have voted for them in the past.
Finally, the Lib Dems don't get any of their policies in Government, when currently, iirc, about 75% of their manifesto pledges are being implemented by the Coalition.
No, that's a fudge - most of that is accounted for by the things the three main parties have in common (much of which is already fudged: "we will protect the NHS", "we will put Britain at the heart of Europe", "we will invest in these things that everyone likes"), or things that they at least had in common with the Tories (scrapping the planned voluntary ID cards system). So yes, they would get some of their policies in government under a confidence arrangement - or even just in opposition, as all three parties do after every election. Hell, I'd wager the majority of Lib Dem manifesto pledges would have been implemented even if every Lib Dem MP had spontaneously combusted the day after the last election, and their seats left empty in memoriam.
For the things the parties don't have in common, they could easily horse-trade with the Tories - as they did in the coalition agreement, but in a more targeted way and without giving hostages to fortune. Indeed, the fact that a minority government is so vulnerable to censure motions gives a party or parties propping it up more power than if everyone is formally committed to a coalition (that's how the SNP were able to ram through a referendum on devolution in the 70s, much sooner than Labour wanted or anyone imagined).
To underline how different things could have been: If the Lib Dems had gone for confidence rather than coalition, then we'd still have had an AV referendum but it would have passed. The electorate rejected AV to punish Nick Clegg, because he has come to be seen as the most self-serving liar in British politics (and that's not a fair view, not least given some of the competition mentioned in this thread, but it is a popular one). Confidence rather than coalition, not voting for tuition fees or supporting Lansley's NHS "reforms" etc, would have delivered AV - and,
to get back to the topic, that would make "Prime Minister Nick Clegg" a distinct possibility for the future.