Touchpads are for PC gamers. It allows you to play KB+mouse intensive games with a controller because one trackpad can be made to work like a trackball (with inertia and all) and the other like a radial menu so it gives you precision and lots of inputs. You’re obviously not going to be top competitive with it, but anything you can imagine using a trackball for becomes available.

But aside the touchpads (which like I said are meant to target specifically PC gamers) it also has back buttons (which make lots of things a lot more ergonomic, e.g. old games where you hold A to run thus removing your thumb from the camera controlling stick, or games made for keyboard that have lots more inputs than what fits on a controller), gyro (which makes fine aiming on shooters a LOT more bearable with a controller) and capacitive sensors (which allow you to detect if your hand is somewhere, which means you can only activate gyro when touching the trackpad or ratchet the controller to reset aiming for games that don’t like mouse input for aiming or even possibly allows you to do crazy things like switching the layer on your controller making it so that if you’re playing one-handed whole drinking coffee the inputs on the rother hand change to give you the extra buttons you might need).