While reading George R. R. Martin's A Song of Ice and Fire series and Martin's many descriptions of elaborate armor sets and weapons, I had to wonder why fantasy RPGs still don't offer gear customization like that. Many games allow customization via selection, but how many offer creative customization?
Certainly, there are good reasons that games which focus on the winning or discovery of items don't favor player creativity. But there are plenty of RPGs in which gear takes a backseat to other thrills. Neverwinter Nights, for example, adhered to D&D's bland item system (Halberd +1, Halberd +2, etc), but was still a fun and bestselling game. Oblivion had plenty of items, but also seems to focus on other goals.
I think games like Spore and The Sims have shown how popular creative customization can be. The outfit editor in Spore's tribal stage offers ideas for RPG gear editors, as do the clothing and tattoo stores of Saints Row and its sequel. And as those games show, creativity needn't exclude achievement. You can offer players new options as they advance through challenges or earn wealth in the game.
Why not? Honestly, I'm surprised I haven't seen this in RPGs.