About the Genesis Device Engine and similar engines. Not everyone has a computer that can run all the latest technologies. I primarily use my labtop to program in and it's not a very high-tech computer and it wouldn't be able to run Genesis. Even though I have a stationary computer that can run it I wouldn't bother developing a game on it.
Besides that. I don't feel it's a good idea to force the contestants to use a specific technology. It likely would keep some people away from the contest, and some people would have been able to create a better game if they had been allowed to use a technology they're comfortable with.