I think he's referring to the gameplay of Halo 3 being better which I can agree with because Halo 3 is my favorite Halo but I certainly don't want them to keep coming out with that same game over and over. There may be differences between Halo 2 and 3 but to keep finding incremental ones like those and implement them with each release... Eventually they'd run out. Now they may have had more time to do that if Bungie didn't crap Halo: Reach onto us but 343 has done a really good job of working with what they have and trying to appeal to fans who loved the original trilogy.
As others have stated above, if you want Halo 3 with 60fps and improved lighting then you may certainly play it. I do all the time.
But you can't make them to drop everything from the game, devolving to original Trilogy aspects, and expect to leave everyone happy.
Also Halo 4's story was the only one to make sense canonically since Halo: CE in 2001.