When playing D&D, you aren't just playing a game.
No, actually, you are. Thats why the word is used prominently on the game books. Thats why WotC's slogon on their homepage right now is "World Leader in Hobby Games."
You are creating a story, and if that means changing the rules to make the story more interesting, that's what happens.
Those are called house rules. They come about because you don't like something about the game system you payed money for. If you're doing it a lot, it's because it isn't a good game system and you got ripped off unless you mostly bought it for the artwork.
The game desingers are not disallowing your cool ideas; they are enabling them.
The game designers (glad you're calling it a game now) made what they called a "role playing game" not a "build your own system" game. They do not, in any way, as you say, "enable" you making a cool shifter by putting a bad shifter in the game. They do not "enable" you with power creation rules, race creation rules or the like. What they "enable" you to do is make a character and play it and if that character is a shifter you're "enabled" to make a very lackluster and uninteresting shifter.
Sadly I have played the worst game to come out of Bioware in 15 years, yes. A pretty bad showing on their part. Their upcoming games are promising to return to their former level of quality.
Three races and three classes, and dwarves only get two classes. Not much variety. D&D 4e? 18 races and 18 classes, with more on the way and plenty of room to add your own or change the ones that are already there.
Thats nice. Final Fantasy XI has 5 races and 20 classes which multi-class for 380 class combinations. Everquest has 16 races and 16 classes. Guild Wars has 10 core classes that multi into about 90 combinations. Those are just three very common games, there are a bunch that have waaaaay more races and classes.
You know, even the Dungeons and Dragons Online warforged are immune to poison, have DR and receive less healing from healing spells.
The game designers make the game playable as a game. The players' creativity makes the game interesting as a story.
So 3.5E wasn't playable because dopplegangers and warforged had more rules that enabled players more play options, but 4E is better because it has rules that restrict what you can do so you are "enabled" to ignore those rules and make your own to play with. Gotcha.