A disreputable bloke on another forum named these sorts of systems one of those "things in RPGs that sound cooler than they are." I tend to agree, a bit. I mean, barring debate of
Ars Magica, these systems never seem to take off.
(I don't count HERO's power-building system here. Even in that system, you generally build your spells first, and then use them as-is in game... unless you're one of the two people on earth who can use VPPs effectively on the fly.

)
D&D's "pick from a list" works well because it's pretty simple to use. You go through the available spells and pick the ones you want tour PC to have. During the game, you can then just say, "I cast X," and you're done. You also have a specific set of relevant rules for each spell that help eliminate ambiguity.
What I do like seeing are systems that build on D&D's to add some flexibility, but without tossing the baby out with the bathwater. E.g.,
Arcana Evolved's hightened/lessened spells, some of the new spells in PHB2 that vary in effect depending on casting time, Warlocks, and so on.