I was thinking about systems with open rules and closed rules. What is the difference?
Well, a closed rule is "you have a sword. If you hit someone with it, you deal 2d8 damage. Who will you hit?" An open rule is "which stats will you use to affect which things in the area, and which aspects will you use for an extra point, and which stats will the enemy use to defend?"
There's a lot of attraction to open rules. Open rules feel like you're empowering the player, and they are also a lot easier for the game designer to write. But it's not necessarily better game design.
A big part of playing any game is expressing yourself in how you play. Open rules initially seem like the best choice for that. However, a player can openly attempt to do random things whenever they like regardless of the rules. They don't need an open rule set to swing from a chandelier - they just need to pester the GM into allowing it.
On the other hand, a closed rule set narrows the focus. The player can now express herself through her performance within those well-understood confines. Not simply whether she prefers to be a magician or a warrior, but whether she chooses that +1 to hit on level-up or whether she goes for the free half-step.
Those are choices that have little or no merit from a narrative point of view. But they have a lot of merit from a "you're playing a game, not just making up a story together" point of view. Moreover, they offer three added advantages.
1) They are easy to get into. Whether or not a player can role play, long before there is any real narrative traction there are the rules. Long before the players have any emotional connection to their own characters, let alone a connection to the Demon Lord Bldhduhgu, they have a connection to whether they are performing well within the confines of the game. Every player can get drawn in, although some lose interest in fiddly balancing later on.
2) They are usually faster. A closed rule situation is built to execute smoothly and easily. They "front load" the most complex and creative decisions, offloading them to the part of the game that is open and largely rule-less.
3) They make exceptions mean more. In an open rule system, something unusual happening usually resolves to a simple +1 or +2 or whatever. In a closed rule system, something unusual usually resolves using a completely different and unexpected set of rules, or breaks the rules you normally rely on. This makes a lot bigger impact on the players.
EDIT: 4) They allow for much deeper tactical situations, as open rule sets are necessarily less rigid and structured as to how the battles progress.
Now, allowing the players to be as creative as possible can be good, especially if you can do it in a framework which doesn't instantly fly off the rails. I generally leave it to the "full open" sections of the game rather than the nitty-gritty rule resolution parts, but even in the nitty-gritty you can allow it or even promote it using a simple "window rule".
A window rule is any rule which allows the players to take any unusual action they can think of. For example, swinging on the chandelier rather than simply stabbing the enemy with the sword. There are a variety of window rules, some better thought out than others.
A bad window rule is "if you can come up with some piece of creative description, you get a +1!"
This rule is bad because it encourages the players to throw in random crap, and punishes the players who aren't as good at coming up with random crap.
A slightly better rule is "you can give an ally a +5 if you spend your turn doing something to help him."
Another decent rule is "the enemy's defenses can be reduced by 2 for the rest of the fight if you spend your turn doing something unusual."
But the basic truth is that if the players want to do cool stuff in combat, they will ask to do it. They don't need a special rule. The GM can encourage them to do cool stuff in combat by offering lavish rewards for anyone who comes up with a cool idea (assuming it isn't the same person over and over), as well as having the villains come up with cool ideas that work against the players.
Anyway, the core of it is that a closed rule system isn't necessarily bad. It really allows the players to jump in and express themselves, and it also allows the game designer to build up some fun and interesting exceptions that feel sharp and exciting.