I think it's a harder question than some are giving credit for. Yes, I would like to be able to carry to, at, and from the stadium. However, given the intensity of emotions that are rampant at stadia (particularly with football), I'm glad that a lot of the people in the dome or bowl with me don't have a firearm. I've seen cops break up fights between grown men in stadiums - men who had the financial wherewithall to pay for expensive tickets, and who probably are fairly law abiding in other parts of their lives.
As for criminals not caring about the rules against carrying, that's only partially true, and only partially relevant. Many a fan has walked into a stadium intending to abide by every rule. After a couple of drinks, some disappointing play on the field, and one or more obnoxious fans of the other team being too close to him, however, some percentage of those previously well-intentioned citizens get so angry that they make some really terrible decisions and become hyper-confrontational, or even violent. The inflamation of those passions and aggressions is, after all, part of the appeal of many sports, including football. Now, those fans, in the calm before the game, certainly do care about rules; it's only once they are inebriated and furious that they slip the bonds of society's rules. So, for them, the old saw about criminals not caring about the rules doesn't hold true, or at least isn't informative - they aren't criminals at the time they decide whether to pack.
And, many stadiums have instituted metal detectors and/or other searches; in those cases, the rules are not dependent upon the forebearance of criminals.
I'll put it this way. I probably would not go, at least with my daughter and wife, to a football game where CC was allowed, even if I were carrying. I'm not so worried, after all, about some sort of mugging while standing in line for hot dogs, but about some drunken idiot deciding to shoot at/near/around somebody wearing the wrong jersey, and where those rounds might go. I probably would go to a baseball game, though, where CC was allowed; I just don't see the same level of bloodlust and fan fury there.
All in all, I think it's a business-owner's decision to make. If a football stadium owner wants to say that patrons must cluck like a chicken to gain admitance, I think he/she has that right; I just will choose not to go.