To be clear, the use case for these buttons is for minimal zynthians with no encoders or switches. The buttons will only appear when “Enable Touch Widgets” is checked in the web-ui, and I don’t think it would be appropriate to ever make that enabled by default.
For minimal zynthians I think its justifiable for there to always have buttons present, as they are the virtual equivalent of switches. And having them at the bottom makes sense for a touch interface so your hand isn’t covering screen content to get to them (like the main action buttons on a phone).
The touchscreen interface already has alternatives to the encoders, so its only the buttons we’re missing. The money saved on encoders and IO board can be put into a bigger screen, which makes the loss of screen real-estate less of a concern.
One reactive UI future enhancement which would be nice is changing the labels and hiding the buttons based on the screen context, but that can be done later.