It's Time for Vancian Magic to Go Away
No, it's not.
It does a good job of portraying the feel of a certain type of magic - the type that is relentlessly sought by power-hungry individuals who aren't born with magic and refuse to kowtow to others for it. Folks whose magic is not their own to be channelled and shaped on a whim, or bestowed by higher powers. Folks who have to struggle to master it through sheer ambition and cunning. i.e. Wizards.
I would be perfectly happy if it went away for sorcerers, clerics, druids, etc - but it captures the very essence of the wizard class archetype in tone and feeling.
I guess, what I am saying, is that it should be in the game but it probably shouldn't be the baseline assumption for the game.
Anecdote (feel free to skip):
When I first discovered D&D, the magic-users with their spells and books seemed so arcane (as in obscure and mysterious) and not at all what I expected. I was eager to see how it worked and to achieve an understanding of it. When I later discovered AD&D I found strange new spells crafted by wizards from other dimensions with unearthly names - Bigby, Mordenkainen, Otiluke, Drawmij. That flavour, that sense of wonder, is what made me love D&D.
Isn't that sort of feeling what magic is all about?
Also, it isn't clunky at all - it works smoothly as a mechanic in-game. It is easy to use, and yet unusual and obscure. A good way to represent "arcane" magic in a game. Neither is it particularly unbalanced. It is no more unbalanced than spell-points/power points for example (in fact, it is not as overtly potent due to less spammability).