Are you sure about that? All the pictures I see of the Kronos K70 had those grooves cut out in the tail cap. I assume it makes it easier for a thumb to press the button.
I don’t think I would argue against not having those cutouts. Since the side switch is what’s going to be controlling on and off and all the modes, the tail switch should be seldom-used just as a manual lockout. I see no issue with making it completely round with no finger cut outs. Maybe I can suggest this to Sofirn.