I don't think that missing a swing should reset your combo, either that or power ups shouldn't be given only for high combos.
I was enjoying myself, just running down the track and murdering guys, right up until I realized I could only get powerups like the horse if I killed 10 people in a row, without missing or getting hit, suddenly I found myself not even bothering to throw my sword or spike the golf carts because those were both very stylish moves that had a delay and put the combo at risk.
The game itself is fun, but the fixation on combos suddenly throws the carefree attitude out the window and replaces it with one of precision and caution, which totally clashes with the craziness of the story and the absurd things that start filling the track.