A person with 12 slots won't be choosing between 4 meganukes or 12 combat-tricks, they'll be just able to equip all the meganukes they have, and still have spots for a few tricks.
It's essentially gutting the interesting parts of Memory as a mechanic.
That's only a very late-game issue and imo it's not a real issue at all. That's exactly how magic functioned in DOS1. For once, you need both a high score in magic schools and you need a high score in memory. That's very unlikely to have in the early game.
What my suggestion actually does is that you have more possibilities the better you become in one school. I think that it is ok to be able to cast a lot of pyro spells when you have skilled pyro to 5. But at the same time it's unlikely until the very end game that you will have one or even two other schools on the same level. So high-level spells of other schools will still require multiple memory spots if you want to use them. My system gives the player more freedom and flexibility in the late game. I'm not that fond of the vision that even a very high class mage for example isn't able to cast more than 4-5 spells, especially since high-class spells still have high AP costs to cast and high cooldown costs (I strongly urge to have very high AP and cooldown costs for these spells/skills). We shouldn't forget that memory isn't the only mechanic that limits the skills you could actually use in combat. More than that, your deck is limited by AP costs and cooldown. It's very likely that you can't use most high-class spells more than once in combat due to these costs. So in the end the low memory spot requirements for high-class spells in schools you have a high score in won't erase the choice whether you want more spells with high AP/high cooldown costs or more spells with low AP/low cooldown costs. My suggestion gives you only more choice because the range of spells and skills you can use in combat would be extended. I personally played DOS1 a lot and one of the best things in character developement was the fact that you had that wide range of spells and skills you could use in combat. That made you flexible in encounters, especially in the late game.
So what I think memory should do is focusing a character's range of possiblities to the abilities the character's good in. It shouldn't serve as a rigid limit to only have a very small amount of spells at hand, especially in late game. I think that Larian should give the player more freedom not less. Memory is good to balance the game, but again it works together with AP costs and cooldown costs for skills. Less memory requirements don't give you a free pass on spamming high class spells. It gives you the chance to make full use of the possibilites a high score in certain skill class or magic schools should give you and it makes the game more fun by giviny you a greater range of spells you can actually use in combat encounters.
