Well, actually the entire BGM of Raging Blast is good in the japanese version.
The problem is that you are blaming the developers who are just people that work and do as they are told. Developing and designing a game is not easy, but there is also the added problem you have to maintain the publishers happy. In the case of Dragon Ball, they have to develop a game in a year, so it's normal they reused assets and the engine. Even dimps have been doing that for years now with all the carddass games they have releases all the budokai iterations.
When the first Sparking game came out, it was really buggy, and had lots of problems, but the truth is that they tried to do something different from the usual fighting 2D game that's been around since Streeth Fighter II popularized it. That engine had a lot of potential and the developers deserve merit. It's true that the games on PS3 are not as good as the ones on PS2, but they also had to redo a lot of the assets and adapt the engine to the PS3. They half succeded doing that, and sadly RB1 was not as good as Sparking Meteor. After that they had to put another game in less than a year (and also the TAG VS game which even though it used a lot of Sparking Meteor Assets, they had to be adjusted for PSP).
If you want to blame someone, blame namco bandai or shuesia.
About Dimps, it's true that Dragon Ball Heroes is very popular, and I like it. But the truth is that is just fanservice and not much gameplay. All characters share the same animations for all the attacks besides the idle, winning and final attack animation. That's really low budget and that's why it's very cost effective. You say that Spike had a lot of chances doing the Sparking games, but the same could be said about Dimps.
SPike: Sparking, Sparking Neo, Sparking Meteor, Raging Blast, Tag VS, Raging Blast 2, Ultimate Blast, Kinnect
DIMPS: Budokai 1, budokai 2, Budokai 3, Shin Budokai 1, Shin Budokai 2, Infinite World, Burst Limit
+ Card games using the same assets and engine: Carddass 1, Carddass 2, Bakuretsu Impact, W Bakuretsu Impact, Dragon Battlers, Heroes, Victory Mission, Victory Mission 2
+ Dragon Ball Advance, but this one is not importan for this discussion.
Both Dimps and Spike had the same chances of doing good games (if we count carddass games, DIMPS had a lot more DBZ games). Dimps did a bit better because even though Burst Limit uses the budokai engine, they tried changing a few things and the end result wasn't bad (it wasn't as good as infinite world either in my opinion), on the other hand, Spike did really bad with the changes in Ultimate Blast, they should have go with RB3 instead and improve what they were doing. It's good they tried somehing new, but in this case it was just simplifying a game instead of doing a new engine.
Then we have Zenkai battle royale which looks like a very good game if we don't count those annoying sound blips when locking into opponents.We don't know who developed it, but my guess is either Spike, or someone using assets from Spike (the game uses the same engine and animations).
What I have seen from J Stars, it again uses the same engine, but really improved. The game seems fun, and I really hope my game arrives soon.
A long time ago I thought the same about EA because they were responsible for the decline in Origin Systems (A great company in the 80s and 90s). Of course you are free to think whatever you want, and if you don't want to buy a game, then don't. But I recomend that if you really see a game that you like, just buy it and forget about who developed or published it. As long as it's fun, then that's what matters in the end.