Yeah, but the difference is that Reagan didn't at one point consider himself to be a moderate like Romney did. (At least, as far as I know.) He always considered himself a conservative, while Romney changed to one when he started running for President.
I am not so sure. If you look at Reagan's position on certain issues
within the context of the times (i.e., '60s/'70s), a case could be made that he was on the left on abortion and gay rights during his time as Governor, or at least one could argue that he was further left on those issues than Mitt Romney was in the '90s. And, like somebody else pointed out, Reagan was a New Deal Democrat for a large portion of his adult life. Funny enough, Romney takes flak for being an independent during approximately the same years in his life that Reagan spent being a Democrat (i.e., their 20s/30s/early 40s).
More than anything, it just goes to show you had absurdly partisan both parties have become the past few decades. This hardline case for ideological purity is probably part of the reason why the country's political institutions are so messed up right now.