Almost nobody cares about replacing their keycaps, even among Geekhackers (of course, the ones who do care are disproportionately vocal and places like this are echo chambers). It’s not worth worrying about excessively for a keyboard vendor building something new.
Staying 100% compatible with Cherry MX keyboards from the late 80s inspired by IBM keyboard layouts from the early 80s is fine, but it should be approximately last on anyone’s list of design criteria.
If you are one of the people who considers aftermarket keycaps important, don’t buy this thing. (Personally I think that’s the least of the reasons not to buy this thing, but I’m glad they’re experimenting.)
Beyond that, there’s a chicken–egg problem. If more vendors tried to focus on building interesting designs instead of making another identical clone of something you could get 30 years ago, we’d see more variety of aftermarket keycaps.