I was going to write something on Romney's rather incredible speech at a private fundraiser, but Reihan Salam beat me to it, and did a better job than I could have, so you should just go read that. Ultimately, the reason we have almost 50% of Americans paying no taxes is that we have decided to use the tax code to subsidize low wage work and childbearing, and because seniors don't pay taxes on all their social security benefits. You may quibble with any of these choices, but as tax subsidies go, they are the most defensible.
Part of what you're seeing is, I think, a break between the GOP wonkbase and its donorbase. The maker's and taker's narrative seems fairly popular among wealthy Republicans, and of course, it is not entirely wrong: there are people who would prefer to live off the government than go to some boring job.
But the EITC is incredibly popular among conservative and even libertarian wonks, on the very sensible grounds that if workers really cannot earn enough by their own efforts to support a family, the best thing we can do is top up their wages to make the work math . . . er . . . work. Even if you don't care about the workers themselves, their children are innocent, and also, apt to become a problem for society if they go half-fed.
So too, the child tax credit is very popular among Republican wonks who generally seem to approve of childbearing. This is particularly important if you oppose immigration, and also, would eventually like to collect your social security checks someday.
I hardly need to go into the full frontal pander to senior interests in which both of the major parties of our great democracy engage. But I might point out that given how many seniors live on their social security benefits alone, it hardly makes sense to send them the benefits, and then tax it all back.
I actually think there is a defensible version of Romney's argument, which is that everyone should have a stake in the costs of new spending. It is structurally problematic that many people have an incentive to vote for new spending without even thinking about the costs. But this is an argument for rolling things like the payroll tax into the general income tax system, not an argument for giving people a bunch of tax breaks and then accusing them of being parasites that you just can't do anything with--hell, they can't even hear you because of the flapping noise their leech-like mouths make as they suck the lifeblood out of The Republic.
This seems like the sort of thing that you should particularly not say if you are proposing a grotesquely irresponsible set of tax breaks which disproportionately benefit the wealthy, instead of, oh, I don't know, doing something about the nation's $1 trillion dollar budget deficit. Personal responsibility is important. But so is public responsibility.