I dunno. It could also be that you need some kind of essence like I mentioned that isn't physical or perhaps you can cast more than one spell but lose all spells the next day, etc. Something that keeps it balanced but allows a little more flexibility?
I know people keep mentioning the whole "scry and teleport in" but then they must have some idiotic NPC's. My group usually had some master sorcerer/dragon/wizard leader who wasn't scryable and who used those opportunities against the group. Sure you might get some minions with it but there's nothing worse than teleporting in finding out you're caught in a spell that delays your arrival and allow them prep time to capture, etc.
I guess I like that you have a few prep'd with just limits on which one is used (like the old sorcerer) but it just feels too stringent on quantity now. I'd rather limit how powerful items can be than bring it to only one of the upper levels. Why can't it be limited to 2 spells but it has to be different spell schools?