Wow, what a novel and unique idea you have all struck upon.
*
Seriously though, it would only increase the cost of the gun, people do build parts guns all the time, but its not any easier nor is it more efficient. We have a functioning system that works for the time being and all grips about price aside we are happy with the state of our sport and frankly its only going to get better with time.
But it is nice that you wanted to share an idea which is always a positive thing.
Cheers
*Im just kidding around no hard feelings