Did you expect to see a game more like the original?
What did they change? They took out multiplayer. They inflated all the prices. They gave you more moves and made the controls less responsive.
You think in the 15 years since the original they might have improved things. Nope, they tried to make the same damn thing over again, and made it worse. 79% is far too kind.
In all honesty, I didn't expect much in the way of change between the NES and GBA version. I didn't really want it either, as RCR was an outstanding multiplayer capable game on the NES.
However, there are differences - the script has been updated (slightly), more reflecting the times, the graphics have been improved, and there's more sound channels being used at once than the NES counterpart. There's also no multiplayer.
Comparing the title verses other GBA games (and ignoring that the NES game ever existed), this game is strictly an average title. In my mind, the 79% overall score reflects that.