Why is the music in the videogames so radically different from Kikuchi's OST?

[Doctor.]

Every track in a DB video game seems to be filled with a bunch of guitar rift. It sounds like something out of a rock concert, rather than something that is supposed to resemble DB or DBZ. Even the soundtrack for Raging Blast which Kikuchi himself worked on, correct me if I'm wrong, sounds completely different to his other work.

[TheGreatness25]

I feel you. It's a video game thing. I guess that's the new direction of the series because isn't that how Super is? I could be wrong.

But hey, not all of the video games are like that. I can't speak for anything before the PS1 era, but I know that Dragon Ball Z: Greatest Legends, Ultimate Battle 22, and Final Bout had more DB-sounding tracks. I liked them so much, I have them saved as part of my music collection. Though, I will admit, that the music for Greatest Legends sounds more like Bruce Faulconer type of work than Kikuchi.

[Jord]

Some of the Tenkaichi Budokai (Sparking) games have midi versions of Kikuchi's score but they actually don't fit that well in a video game since the pace is dramatically different from the anime fights where there is lots of room for dialogue and stuff.

[TheBlackPaladin]

The Japanese versions of a lot of the video games do in fact have synthesized versions of Kikuchi's score. For reasons that are not entirely clear, a fair deal of games got a new score--composed by people in Japan, oddly enough--for the international releases, even when the Japanese voices are selected.

[VegettoEX]

I'd say a lot of the early games (Famicom into Super Famicom era, handhelds included) had music that very much DID evoke the original Kikuchi score. I think once Yamamoto really got his hands dirty (literally? figuratively?) in the 32-bit era and beyond, and personally felt the need/desire to branch out with styles (which he specifically said in his part of the "Legends" bonus text file), things indeed started heading off in new directions.

But even then, I hear a lot of the old style in the Budokai tunes, for example - it's just that they're hidden beneath the blaring guitar at times.

If you want a Kikuchi-scored game that isn't literally scored by Kikuchi himself but sounds like it may as well have been, look no further than Dragon Ball Fusions.