I understand that you are experimenting with the XP and skill system but you seem to be going in circles.
How about a hybrid of A16 and A17 - i.e. you learn experience linked to what you are doing and can only use the skill point earnt in the associated skill tree, for example if you got xp...
A really bad decision to go back to A16 style RWG patchwork quilt style.
You really had something with the snowy north and sandy south style. The burnt biomes should be patchy and only in forest areas. The wasteland should be one area in a city hub that players go for in late game. It should...