I remember that happening and soon after Tekken 4, all the veterans started to come back (i.e. Bruce, Ganryu, Lee, Anna, etc.). If Soul Calibur follows Tekken's ideas (and they will) expect to see Sophitia come back then Cassandra, Xianghua, Taki and Setsuka and before you know it...A whole Soul Calibur roster of all our favorites from previous games are back for one whole game...And it better be canon as to where they've been all this time (especially since Cassandra's been in Astral Chaos, Sophitia being Elysium and all that stuff).
as much as i miss all the veterans from previous games, i actually DON'T want to see them in the next game. i'd rather have the series move forward and add new characters and styles than bring back old ones, especially ones that have been replaced.
really the only reason is because i don't want the soul series to go down the same path tekken did. when i booted up tekken 6 for the first time i was overwhelmed by the character selection screen. thats not necessarily a bad thing, but because the roster was so big, i never really became attached to a particular character. no one seemed to be characterized at all and because of the sheer number of styles, none of them were able to stand out. plus, many of the returning vets who hadn't been in many recent iterations (baek, ganryu, armor king, rodger etc.) and were already replaced with a similar style (hwoarang, kuma, king, steve etc.) made the roster feel even more watered down. throw in the fact that lots of characters already fight fundamentally the same way, (i.e. jin, kazuya, heihachi, or eddy and christie) made me feel like the characters were already shadows of thier already watered down remains. now that's not to say it was a bad game, because i liked tekken 6. it just didn't have the same impact on me as other fighters did.
so i'm worried that if we bring back all the vets, we might end up getting a clusterfuck of characters who might have differences here and there in their styles, but the overwhelming number of similar characters might make the game feel...well, underwhelming.
think about it. scv has 3 sword and shield characters. sure none of them are sophitia or cassandra, but do we really need two more s&s characters? plus, they've already run their course with the story. i'd like it if project soul just gave us some closure on what happened to them, then close the fucking book. it's a new game, and we all gotta move on.
i dunno. maybe some people like giant rosters, but if i dont connect with my character, i won't like the game. but that's just me personally.
TL:DR: tekken 6 brought back all the old characters. lots of styles felt similar and rehashed. overwhelmed and couldn't connect with a fighting style. ended up not liking tekken 6 as much as other fighters, and i'm afraid if sc6 brings back all the vets, the same thing will happen.