Hard to know without looking at how their system is set up in the code but because something isn't hard doesn't necessarily mean it isn't still time-consuming and costly.
Not feasible might simply mean costs more money to implement than it's worth, which is something we can't know just because it can be done roughly with save file editing. That doesn't count the UI implementation or debugging that has to be done for an official release.
Either way, I'm happy...
I agree that it's an enormous waste of time and money but it's too late for them to take it out of the series, unfortunately. If CAS was never in the series and they simply had better graphics, netcode, more characters and stages along with decent single player modes all at launch, I think it...
Every other guest character appeared after their most recent game was released. Why would this time be different? Especially since Project Soul and Namco are using the love that people have built for guest characters in their native games to help them sell SC6 copies and not the other way around.
Haohmaru is confirmed and Hwang and Setsuka are pretty much locks for the next two slots, IMO. I think Aeon gets the last S2 slot, since they can sell the pass off the strength of Haoh and Sets.
Then Hilde, a new guest (maybe Cloud or Sephiroth), a brand new character, and one returning...