There is HUGE replay value when I can go back into the game and choose a different set of playable characters that give me different strategies in combat along with different content in dialogue.
Sometimes I even choose the entertaining hero that sucks in combat an thereby makes the game more difficult, but I choose that hero because he's my favorite 'character'.
I also love when certain characters are difficult to recruit. You may have to do several quests and conversations in a very specific order to get them. Or you may have to already have certain characters in your group to prompt certain conversation that leads to a new character being willing to join you.
[edit] of course I don't mean 10+ at the same time. If its 4 guys in a squad, I want to struggle with deciding who will be with me and who will sit back and not earn XP.
I also love the situation where I drop one of my high level mains for a Low Level guy/gal I just met, all because I'm visually intrigued by the character design