but given the apathy among app developers for apple watch, and this being such a small segment of apple watch users, are developers going to bother to rewrite software to give a unique experience to a minority of users? As you say, if there was actually a demand for it, then it would be across the range, lots of people are going to be using the screen in the pool but wont have shelled out for an apple watch pro.
if there was really a demand for this button to 'select a menu option' then apple at any stage could have allowed the present side button to be configerable. i only use it for apple pay, but tbh if they'd put double tap on crown for apple pay it would be exactly the same. Shuffle apple pay to double tap crown, make the dock a double tap on the side button for the (for me) useless dock, and there you have, a button spare for whatever this new button does.
my point is less about whether a button could be useful (not for me, i could happily have a button less if you moved apple pay) but whether having differnet amounts of buttons on what is likely to be a small segment of the market, especially given that whilst there has been a decent increase in the number of AW users, there's a noticeable decrease in interest from developers with hardly any new apps and lots of existing apps being binned.