Magic, for me, is the biggest sticking point, not characterization. Magic in novels serves the plot. When you read about someone picking up magic item A, you know that he or she will use it at some point in the future. And, it will be the perfect fit to solve problem X. Sam will use the glowing potion to foil Shelob, the hero will have those flying boots and an invisiblity helm at just the right time, etc.
In RPG's this is almost never true. Magic items and spells are tools for the players, not for the plot. The player chooses to use or not use a given magic item and its efficacy is dictated by the situation, again, not by the plot. Look at any character sheet over about 6th level. I will almost guarantee that there is a potion on there that the character has had for the last four levels and likely will for the next ten.
This is a trope that you never see in novels. The idea that The Hero picks up a Magic Arrow and then never uses it until he dies horribly under the claws of Random Monster Z, is not the stuff of good fiction.