My theory on Romney's bad handling of this tax return business:
I agree with the consensus that he should've known better and been prepared for it. However, I think a lot of his bad handling of it has to do with deciding to focus on his business experience than his one of governance. Although Romney did destroy the competition in the primaries, I think it is notable how many times his opponents continually brought up his tenure as Governor of Massachusetts as a negative against him (both in 2008 and in this primary season) to show he can't be trusted with conservative ideals. Arguably, even up to 2011 he seemed set on going with his political experience (at least that's the impression I got) and a lot of us on this board (myself included) predicted that he would be destroyed in the general election because of his flip flops. Also, MassCare (or whatever it is called) is pretty much all the ammunition Obama would need to riddle Romney to death come November.
Arguably, Romney probably didn't see using his experience at Bain as a major part of his campaign as it doesn't have that much to do with the political process. He and his team probably didn't plan for it, like they did trying to defend and make his experience as Mass Governor look good (which seems to have proven to be a very improbable task). After it became clear that wasn't working, it seems that Mitt finally decided on the one area that the team anticipated people wouldn't find a treasure trove of attacks from: his business and financial career.
Many of us were facepalming at why Romney decided to make his handling of the 2002 Winter Olympics as a major part of his sellability, but in hindsight it makes some sense. The 2002 Winter Olympics, nobody and their grandmother remembers it. Athletes who won gold medals there probably don't remember it. So while "I ran the Olympics" isn't exactly a winning issue, only a very desperate opposition would look for negatives with it.
I imagine this is what Romney mistakenly thought about Bain Capitol at some point.
I should note that in 1994 Ted Kennedy had actually planned and even shot an ad that attacked Romney's tenure at Bain Capitol. But, after Kennedy crushed Romney in a debate he felt it unnecessary to use the ad, linked here:
http://www.youtube.com/watch?v=BdYx19temU8And now Romney's tax returns are being asked for, among other things. It just doesn't matter how successful Bain Capitol was as long as the narrative of the rich man who fires people and hides things is set by Obama. This is gutter politics at it's finest, but Romney should've seen it coming. What he needs to do right now is just stop whining about the dirty nature of the game and just turn over the documents. It might be nothing, like Obama's birth certificate (which he waited forever to turn over for some reason) or it might be the biggest scandal since Watergate.
The GOP seems to have dug a hole for themselves with Romney as the candidate. It seems very hard for the man to come up with some sort of experience he has had that can't be turned into something quite negative. Thanks to Romney's failure campaign Obama might be one of the most disliked presidents to ever win re-election (emphasis), along with Bush Jr.
Romney most likely won't go to jail for anything, but this is still a very bad situation to be in and it won't be better until he releases the forms. Whether or not the forms have Earth shattering information in them.