Someone did. 
(Sort of; it's at the app, not driver, level, and like the Hue Dimmer, it responds to all taps rather than waiting until you're likely done.)
Do note that there is a limit here that I didn't see mentioned above: if you hold the top, middle (if it's a 5-button), or bottom button--basically, any button that wasn't "designed" for dimming--down for more than about 5 or 6 seconds, you won't get the "released" event (with the fast driver, or I don't think any event with the regular driver). This is likely because Lutron didn't intend these buttons to be used that way and reserves at least the bottom button, usually, for programming/activating the Pico. This is likely longer than you'd hold the buttons down anyway and assumes you want a "dim/brighten while held" thing (sounds like you do), but I thought I'd mention this in any case.
