So in my games of D&D we have some custom rules for what we call Terrain Effect.
Fighting an Alchemist in their Lab, lots of volatile chemicals around so a stray Fire Bolt could cause an explosion.
In a Volcano fighting a Dragon, watch out for those pools of lava.
Caves of ice are slippery and cold.
Stuff like that to make an encounter feel special. I have never see an cantrip create a AOE on a stone dudgeon floor.
I don't have an issue with Fireball leaving some fire behind. Also that why there Wall spells, to create surface effects.
I really hope they give us options to remove Cantrip Surface Effects, Dipping, Elemental Arrows and Bomb so I can have a game closer to what my group plays in 5e. I think have a House Rule tab in options where we can turn off these house rules from Larian Studio would be the best approach, some people want them, I just don't.
Why would you ever cast a wall spell when Fireball, already the most powerful effect in the game for its resource cost, also does continuous burn damage?
Maybe the most powerful spell in the game shouldn't be more powerful?