I'm sure everyone's noticed by now the sharp divide between gamers who want open-ended systems ("rulings, not rules") and those who want more detail, more balance, and more design built into the system. This argument has only been going on for, what, a couple decades? The first group like adaptability and complain about rules that straight-jacket the imagination. The second complains about the arbitrary nature of open-ended systems, the potential for abuse by GMs, and the lack of guidance for a new GM.
I'm not going to talk about which side is right, here.
Instead, I'm going to point out something. Something you can do with a stricter set of rules that has detailed lists of traits, feats, skills, classes, races, spells, and powers.
Players can plan.
If you have an open-ended system that players and game masters can improvise with, character can do practically anything. All it requires is a GM ruling, perhaps some group discussion. But by that same token, in between sessions, there's no way to determine what you can do. If you're a GM reading an open-ended rulebook, you can get an idea and say, "hmm, I think I'll do that this way." If you're a player and you get an idea for something that's not in the rulebook, you have to wait and ask the GM if you can do that, and how. Since things outside the rulebook aren't set in stone, you can't really plan ahead too far.
But the more complete a rule system attempts to be, the more you as a player can use the rules to "play between sessions". You can go shopping, either literally using equipment lists or figuratively using spell, power, and skill lists. You can try out various "character builds". Character creation becomes practically a game in itself. Sometimes, you can literally play between sessions; TFT had a job/income system back in 1980, and some games had random event systems that could be used during downtime.
I am a great lover of the open-ended approach and dislike the list approach. Still, I have to acknowledge that systems with strong character-building emphasis and detailed lists of available abilities tap into a powerful desire that lighter systems have trouble fulfilling.