I'm not sure what interface element they'd have to use to represent working the hi-hat pedal. It'd also be fairly hard to explain to the uninitiated, I imagine (since this setup would be pretty daunting for a casual player). Double bass is pretty self-explanatory (you can't hit every bass line with a single pedal so you need to learn to alternate your left and right taps to cover each one) but a cymbal you work with your foot isn't as easily translatable to representation of the kit.