Celebrim
Legend
They took away that trope as they powered up the base magic user into the modern wizard.
The Wizard has to specialize to get fine control and only in their specialized school.
For the wizard to get fine control generally again You would have to hit it seriously with the nerf back which no wizard fan wants.
Sure but we are talking about some hypothetical perfect new edition which could incorporate new ideas like Monte Cook's built in metamagic where each spell had a powered up and powered down version that could be spontaneously metamagiked as one of three spell levels. Surely that would give us finer control than ever?
In general, spellcasters right from the start of playing with them have proven overpowered in play. They need some sort of restriction. Non-spellcasters need ways to counter magic. Magic has to be somewhat onerous to use. Wizards have to be crunchy and good with ketchup, or whatever. The pressure is always coming from certain parts of the player base to make magic "more fun" by reducing the restrictions, but then they also want it to be "more fun" without hitting it with a nerf.
At which I point them at Celebrim's First Law: "Thou Shalt Not Be Good At Everything".