ATTENTION MODERATORS. My latest ban (14-day ban from Qbix89) is not legitimate, take a look for yourself. Please review this before considering me a "repeat offender". Thank you.
They couldn't because people, including myself, wanted a different game with fixed mechanics.
For example, I imagined Reach having an entirely new ranking system. Halo 3's was highly abused and, even in some areas, broken.
Halo: Reach did get a new ranking system. Is it any good? Hell no, and it especially isn't any better than Halo 3's.
I would also like to point out that Halo 3 is indeed superior to Halo: Reach, and always will be (in a historical and statistical standpoint). It was more popular, and it was much, much more successful. That's a fact, and there's nothing anybody can do to change that.