I recently got Street Fighter X Tekken and I really do like it. Since I got it with the Street Fighter 25th Anniversary Collectors Set, I have all of the bonus characters and costumes included at no extra cost, but it still feels very weird downloading a 100KB "unlock" file. I love the fact that these characters and costumes are on the disc, personally. It increases compatibility online, it doesn't hugely separate the player-base like the many versions of other fighting games, and you don't have to download a gig of character models, animations, sound effects, voice-overs, and arcade mode cut-scenes just to have the "complete game". However, it still stinks that you have to pay an extra $20 to unlock them when they're already finished and on the game disc. So how could Capcom have done this in order to minimize the backlash? Simple: make them bonuses to people who bought the game new, almost like an online pass.
Think about it: Capcom/Dimps spent a lot of time and effort making this game and they deserve some kind of compensation for that effort. If you buy the game used, you're effectively robbing them of their profits and costing them money by using their network. This is why the game has so many microtransactions and "DLC" *cough cough*. Capcom wants to monetize the copies of the game that don't earn them anything directly, and I am completely fine with that. However, this also hurts new buyers. If the game included some kind of bonus one-time code to instantly complete the character roster, it would have solved the problem with little fuss.
Now there are some problems with this solution: 1) What about people with no internet connection? 2) What about tournaments? 3) What about bringing your copy of the game to a friend's house? 4) What about 10-20 years down the road when these unlock codes won't work anymore?
There are a couple solutions to the above problems that would definitely help. First, the game could have a "tournament mode" switch that disables everything except options and Versus mode, but unlocks all of the characters temporarily (with no saving, of course). Rock Band Unplugged has a similar option that allows you to unlock every song in the game instantly but with no saving. The second option would be to allow the characters to be unlocked manually like older fighting games and Smash Bros., each with different criteria which may or may not take a long time. For example, you could unlock Mega Man/Pac Man by beating them in Arcade Mode if they randomly show up, for example, or some of the other characters by playing Versus mode so many times or for so many hours, completing so many missions/trials, or even buying them with some kind of in-game currency that would take a long time to build up.
Of course, for those who buy it used, they could also just go the easy route and instantly buy access to them all online. Burnout Paradise does this as well. You can manually unlock every car on the disc, but you can also pay for a "timesaver pack" for a few bucks (I think $6-7) to instantly acquire them all. Capcom could have used this approach with SFXT and they could have made more money as a result due to there being less backlash and probably more sales of the game.
So what do you all think? Some of these ideas might have been shared before, and I'm sorry if I didn't notice that, but I think that this is a pretty good solution myself. The only excuse gamers would have at that point would be a sense of entitlement, I think.