LogFAQs > #975289905

If the game went to level 20 they'd have to cut out the iconic level 20 stuff anyway. You can't program Wish or Time Stop in a manner satisfying to what they bring to the table

And I also think it's a big thing of Larian's game design, is that battles are big tactical events that can take a while, so if they were to fit so many levels into the game then you wouldn't have any time strategizing with your new tools before they're outclassed by your next tier of spells or abilities.