Capcom is too busy teasing fans. Capcom is milking them hard. They think that if they buy enough games with Joe's cameo then that will show that there is support for Joe, then Capcom has to see that Joe has a fanbase and will have to make another game.
Joe has cameo'ed in more games than he was actually been in.
>Marvel vs Capcom 3
>Bayonetta, she recites a line that is Joe's catchphrase
>Wonderful 101, Silva is on a phone call and mentions Joe
>Tatsunoko vs. Capcom: Ultimate All-Stars
>Puzzle Fighter mobile
sad thing is I know I am forgetting a few.
But yeah, why take the effort and resources to make a game in a series, when if you just slap that character in a game it sales increase.