With Great Power Comes A Need For Control

I recently showed my static mana plan to my mother, the woman who raised me in modified AD&D. She liked the concept and implementation, up to a point - she raised concerns over it being too much power for a low-level character. My original thought was that, yeah, a 1st level mage might end up being able to cast 18 magic missiles, but magic is to a wizard what a sword is to a fighter, and the latter aren't restricted to how many swings in a day.

But then I thought about some of the other system changes I'd made from 1st and 3rd, and how weaponry and armor, as well as multiple attacks, have less to do with your class and more with your inherent stats. A mage might have stats optimized for casting, but if they'd taken fighter as a class instead they'd be no better off in physical combat. Any class can wear any armor, and my spell failure for arcane magic is based off of how much metal is in the armor rather than how much it inhibits arm movements for somatic components (something which seemed far too easily remedied with careful manufacture anyway).

So maybe I'm being too nice to casters.

Rather than come up with a system that limits how much mana is available until the maximum is reached, however, I thought about the possibility that spells might, at first, take more mana than would be indicated by their level. Say, for example, that at first level, a 1st level spell costs 5 mana instead of 1. You're just starting out in the world of magic, you haven't had a lot of practical experience, and you're still learning how to properly, and efficiently, wield the power you have. At second level, the cost goes down by 1 point. At third level, it now takes 3 mana for a 1st level spell, and so on until you reach the minimum of 1 point for a 1st level spell at 5th level.

Every time you gain access to a new level of spells, the cost of them is X higher than normal, let's say 4. That would mean that 4 levels after you start getting spells of that level, they would cost the normal minimum of 1 mana per spell level.

This could be a bit confusing for cantrips, since they normally take 1/4th of a mana. I could start them at 4, or I could be nice and start them at 1, dropping by 1/4 each level until the minimum.

Thoughts?