Because low to mid level D&D is much more interesting to most people than high level play with overpowered builds and broken abilities.
Wrong. Pathfinder Kingmaker becomes great once you reach lv 8+. And PF:WoTR will feature a Liches that can become godlike to the point to granting divine spells to the undeads that they create, azatas with dragon companions, swarms that can talk... BG3 in other hands, start with you escaping a mindflayer spelljammer ship who fought a draconic army and there you fight the might, all powerful, extreme iconic intellect devourer.
PK starts falling apart mid- to high levels, because this is where spellcasters get the powerful aoes and the enemy ai doesn't know how to move out of aoes. The few high level spellcaster battles exemplify further that the ai also doesn't handle spellcasting well. So no, as much as I like PK, the game handles low level battles better. E.g. wererats in the cave in chapter 1.
Picking flashy spells for your wizard is not what makes combat interesting. It's how the enemies use their spells and abilities that matters. And usually what happens is that they get more hit points, stats, spells etc., but are stuck with the same ai as their low level brethen.
