Yes, a lot of people here have removed all that stuff.
I for one have only removed the front reflector (no room for it with two headlights) and the dork disk once it became all cracked and was made of very cheap plastic anyway. Rear reflector, yes I removed it to place one of two taillights. Technically in violation of state ordinance but the light I replaced it with has reflective properties so I'm sure it's OK. I doubt any cops around here will care as long as the lights are on.
I still have the wheel reflectors on and will leave them on as long as they're still intact and not falling apart. I have also added reflective tape around both sides of both wheels, so I'm not too worried if the wheel reflectors are there or not. I would love to find a way to mount a little LED, battery, and switch inside them, though.