If doom 3 came out and nobody purchased it I am sure ID would try something different, but when they know they can make a few more million doing the same old shit they WILL.
This was discussed so many times before that I am getting tired of reading this kind of shit.
Just because it sells, it doesn't mean it's good (I.E, Britney Spears, Backstreet Boys, and movies like Scooby-Doo and MiB II ) .
The fact is, that gaming industry now is BIG, and it reaches MILLIONS of people. And people are just STUPID. Is it so hard to see that?