I hate bottom switches, touch or not. In any case, it's not a stretch to add a touch trigger to any device with an MCU. The latest MCU's typically have a CTMU (charge time measurement unit) built into them which provides the required functionality for a capacitive touch sensor. Actually kind of surprised I'm about the only one I've seen building the capacitive type into a mod. People are doing the resistive type with a MOSFET, but the capacitive ones work a lot better and they only require one contact point. I think the latest Atmel MCUs have a CTMU so for those using Arduino, shouldn't be a big deal to add a touch trigger.