Modding controllers was allowed for the reason Moll points out: some controllers come out of the box as able to do NBTs. I've had two of them arrive at my doorstep that way, and I know for a fact KVD's is the same. This would be an unfair advantage to the players who just happen to have a good controller. Either that, or everyone would just go find a controller that suits their needs. In the end, having this knowledge and being open about it (and how to go about achieving the desired result) just levels the playing field. This level playing field has allowed this game to be pushed to the limit by the best in the world, all the while using strats that were intentionally coded into the game.

One thing about modded controllers in other games or on other systems is that being able to press Left+Right at the same time allows you to move faster in one direction. Super Mario World is an example of this; you can fly to the right as balloon Mario or in a Lakitu cloud at double speed with a L+R press. Same with Zelda II on NES, L+R really messes that game up, as it does on Battle of Olympus and several other games, I'm sure. In SMK, pressing L+R does nothing to actually increase your speed, it just allows you to continue steering without losing input for a frame. MKSC is the same way and has allowed modded dpads for the same reasons.