Quite a few android games include a back option. It might not work that well with this type of game (most are on VNs and other navigation types), but a back/next option on the dialogue and a back option after choices wouldnt be a bad thing to have or add.
The touch seems rather sensitive. A single very quick tap seems to work more reliably but the response time is literally splits of a second making it very easy to lose a page(s) of dialogue with no way to reverse.
So the thing is, those android games are done using the Renpy engine, which comes with that back option built in, and it works there because the gameplay flow of visual novels are usually pretty limited (you mainly just advance the story and choose from a very set path.)
Coding that sort of rewind feature in any other genre of game is actually ridiculously complicated, such that the only ones that feature it, usually have their game built around that feature (Braid for example). That's why it's weird to me that you think it's shocking not to have a back button, because aside from renpy developed visual novels, there isn't a single game out there that can afford to have a back button.
You're actually the first to mention having issue with the touch sensitivity. If more people mention it being a problem, I'll consider looking into it, but otherwise I seriously recommend using a stylus, which should give you a lot more control.
