I think this is a nice-to-have. I don't think it would warrant the extra cost and real estate of an extra button. There is a cost to every feature you add, and it wouldn't be possible to make the hardware as feature rich as the Analog lab software. Should a querty keyboard be added so you can search for sounds without leaving the Keylab? Would it be worth it? I really like Keylab's focus on the hardware, and keeping the LCD screen basic, unlike the NI controller which is trying to replicate the complexity of software in hardware with an colour LCD screen, which is a fool's errand.
Perhaps it could be a superuser feature though, such as if you press the Category and Preset buttons at the same time? I think this would be possible with a firmware update.