I don't know why it has to be one or the other; I don't see why developers can't offer a good solid fighting game(with some variety in fighting styles) and still have a big roster. It wouldn't be too hard, especially this generation. I've said before that I'd love to see more of a fighting system that plays like MVC3 or Tekken but at the end of the day
Rocketman has a point; the fighting styles between characters aren't all that different. As a fighting fan, having a game play like a classic fighter would be awesome(there is still Super DBZ of course...) however I'd still be satisfied with a game with only slight variation in character types. I don't want to see carbon copies of characters but it also doesn't have to be too complex.
The biggest Problem I've had this gen is that the developers have taken away content since the days of BT3 but also bring it back and advertise it as "the first time ever in the series!" It's the biggest cop-out I've ever seen and it's basically like flipping the bird at the fans. RB2 was the biggest middle finger when it came to "new features."
As for the subject of multiplayer, putting it ahead of single player in any franchise(not just DBZ) is the biggest foul any developer could ever make. Single player should always be front and center with multiplayer as a bonus or separate entity. This notion that shit has to be taken away to make multiplayer better is just B.S.
I feel like Spike hasn't really learned anything this generation; even if they are forced to make a game every year I'd at least expect to see little improvements not amateur mistakes. It seems like for every one thing they do right they do three things wrong:
Raging Blast
add online play...loose most of the roster; bad controls and sloppy camera.
Raging Blast 2
fix the camera...alter the controls again;give you "new characters" and many SSJ3s
Ultimate Tenkaichi
Find a balance between Budokai and Tenkaichi...Rock, scissors, paper; terrible audio problems;
TAKE AWAY CHARACTERS FROM RB2 
...Wait what are you doing? Are you still reading this? I finished what I had to say, why don't you move on to the next post?