Enemies don't abide by the same rules...for some reason.
They don't care about spell slots.
When I am DMing I mess with creatures a lot, but spellcaster levels I dont haha. Its just too powerful of a mechanic.
What is the problem you are solving? Does your proposed change solve the problem? Is your change feasible? What else will be affected by your change? Will your change impact revenue? Does your change align with the goals and strategies of the organizations (Larian, WotC)?