Just because you can modify the controls doesn't mean it's a good controller for all use cases.
For example, it would be very difficult to do an ultra move in Street Fighter IV on one of these pads -- i.e., quarter-circle-forward x 2 (LP + MP + HP). A standard d-pad with tactile buttons is much more precise.
Might work for some people, but I'm personally used to using a fighting gamepad that has six face buttons in the standard 'Capcom' orientation.
People who learned Capcom fighting games on normal pads are usually OK with triggers, but I learned on a stick, so using the triggers goes against my muscle memory as I still use a stick regularly as well. My fighting pad, however, is much more portable than my stick.
For example, it would be very difficult to do an ultra move in Street Fighter IV on one of these pads -- i.e., quarter-circle-forward x 2 (LP + MP + HP). A standard d-pad with tactile buttons is much more precise.