I said "amazing" and that it's still a great game. But to answer your question: hardware/software capabilities and innovations, and everything else that goes along with more investment over time in a new technology/medium. Was pong "good for its time?". Yes, yes it was. But its pretty lame now. Sometimes things change. Halo is still great, but it's silly to say that many aspects of it haven't been overshadowed time and time again. Part of the reason it was so good was because it was innovative. All those games you've mentioned are classics, but that doesn't mean that time doesn't expose their drawbacks.
Not every game ages though. Would you argue that Tetris is outdated?
I'd argue that, yes Halo was innovative, but as a post above this one mentions, it didn't lose it's identity until Reach. They built on a very strong foundation innovating on top of it, instead of completely changing. Halo 2 sold more than Halo 1, Halo 3 sold more than Halo 3. Halo Reach sold less than Halo 3, Halo 4 sold less than Halo Reach. Halo 5 sold less than Halo 4.
When they diluted the core of the game, it didn't resonate with people as much, and the solution you suggest is change it _even more_... when it's clear that they were not able to take what made it good in the first place and iterate on it. I don't really trust that any changes they make could be anywhere close to the heights that Halo reached with the original 3 games.