Excellent point. I will be purchasing a pair when they release this month. But the one annoying thing, is I have to activate Siri to adjust the volume every time versus having a touch capacitive function like you indicated.
The other fact about the Airpods, is if You only use one, it can be used for calls, but you will need both in tandem for music.
I definitely see the Airpods evolving heavily in the future, more discreet, more color options, sound quality, battery life, ect.
I thought I've seen somewhere that if you only put one in, and then close the case, the music automatically switches to mono-audio for that side. Not certain about that and it doesn't solve the volume problem