They would have made FPS games even if Halo didn't exist. Come on now, FPS games existed before Halo, and they continue to exist after Halo.
I do agree that without the success of Halo, perhaps the Xbox 360 might not have taken off, and that would have been a damn shame. I've gotten a lot out of my 360 (hasn't broken down even once, but then again, no console of mine has ever broken down. My genesis still works) and I'm glad it's successful. They are a worthy replacement for Sega.
I enjoyed the Halo games. Didn't play the second one, but I liked the first and the third. First Co-Op game I ever played. Granted, 70% of the enjoyment I got out of Halo was through playing it with my brother, but I'm still grateful.
Is Halo the best game in the world? No, because there is no such thing as a best game in the world. Is it a particularly stunning example of art in games? No, but how many games are? No, Halo was fun for me. I don't play it anymore, probably never will again, but what time I spent on it, I enjoyed.
And Millions of other people enjoyed it too. That's a fact. Some people don't like it, and that's fine for them. The fact that they didn't have fun doesn't take away the fact that I did, or that you did too.
So stop getting all bent out of shape over Halo haters. There are haters of everything under the sun on the internet. You're asking "why are people being so mean on the net", well, that's not a question worth asking.
It's well known that people in cities are often ruder than people in small towns. This is because when you are in a big city, you get the feeling of anonymity, whereas in a small town, everyone knows each other and you are much more likely to have your rudeness reported.
So envision the Internet has the largest city possible, then take away the police and allow everyone to wear masks all the time. Got a picture of how people would behave in such a city? There you go, THAT is the internet.