Honestly, would anyone care about flight if it wasn't in Solasta? The majority of CRPGs don't bother with a flight system and nor did the many D&D implementations on PC I've had so much fun with.
I don't have a problem with them adding it, but I feel like they'll add something which will be a flight tag that just lets a character ignore most terrain and possibly get knocked down. People will have been instead expecting some hugely complex system and includes different levels of altitude and all other nuances and we'll just have the same exact threads about how the flight system is insufficient.
For me personally, I would not get to hung up if the game didn't have actual flight. But I see what your saying in regards to the levels of altitude and nuances and the complete meltdown threads that would result when it is an absolute certainty that there would be people that see it as insufficient or how they vision it personally in their minds eye.