Well i mean think of it this way in a track you can put a key (s) into the map and, you have to go find it, then there is a door you can use the key you picked up to go through the door.
Most people that play Free Rider, also play lots of other stuff. And that means that they end up wanting cool features from every other game integrated into Free Rider. This would be fun, but they already have something for that. IT'S CALLED HAPPY WHEELS. Free Rider is about a guy who rides his bike in a beautiful terrain. KEYS AND DOORS? GO PLAY ZELDA!!!
In my eyes, Free Rider HD is like Red Bull Rampage. You make a run, and complete it as quickly and awesomely as possible. And if not Red Bull Rampage than it's like setting up jumps in my backyard and trying them, except in a game. Free Rider is NOT an adventure game or a puzzle game. It's creating things and riding them. if keys and doors and teleporters are added, the game wouldn't even be the same anymore. Free Rider for me is like amateur dare-devil, evil knievil and I don't die. I don't want to spend my time collecting keys.