Why do people argue about the merits of film or literature? Why do people bother discussing the finer details of instrumental technique or the creative twists of music theory in a song? I think it's plainly obvious why, and it's no different here than it is anywhere else. I even gave you an alternative answer if you're inclined to ignore the obvious ones, and my guess is you simply don't care for it. Sadly, this makes it no less viable. You may find it annoying, but a majority of what I personally enjoy *doing* with my hobby-life is discussing the artistic and mechanical merit of the things that I enjoy, and I imagine plenty of others do as well. Just because it comes down to a matter of taste doesn't make the discussion worthless. We've already well established that Halo mostly comes down to a matter of taste and what deficiencies one is willing to put up with in their games (this stuff is different for everyone), and hence the conversation in regards to all that has pretty much stopped. So my only point is directly in relation to the comment that someone wouldn't get why people argue and discuss this stuff.
Games are one of my biggest hobbies. What in God's name makes you think I'm not going to want to discuss what is one of the biggest franchises that exists? You may not like my opinion of said franchise, but that shouldn't mean that you find it unfathomable that I might have one, or that I might be interested in the opinions of others in regards to the same thing. I don't really care if others feel differently than I do. Even if I don't like Halo, that doesn't mean I'm not interested in *why* others do. In fact, it would stand to reason that I'd be *more* curious, not less. If I liked it, I'd probably like it for most of the same reasons that everyone else does, so what need would I have of anyone else's opinion on the matter?
And as I've stated already, my interest in making my own viewpoint known and detailed here in the past is so that I wouldn't come off as a tool who's just bashing the games for no reason. Many people will accuse one of such in the face of a popular franchise (and it's happened here already), so I want people to know the actual reasons I have for it not being my cup of tea. That doesn't need to equal condemnation, confusion as to why I might want to discuss it, or disbelief that a cultural phenomenon might get talked about, made fun of, or just be something of a general public spectacle either under praise or admonition. We don't have to fight over it, but at least acknowledge that people are going to talk about things because... it's what people do. Why else do we come to a message board? To talk.
EDIT - I hope that didn't sound too confrontational. Not trying to get anybody's ire up, I'm just trying to state why exactly people like to talk (and maybe sometimes argue) about these things. I hate it when I get made out to be a troll just because I'm interested in discussing something. I wasn't that big on Half-life 2 either in certain ways, and I got really fucking tired of being sniped for making legitimate complaints about its design. That didn't mean I was trying to rag on it just because, or that I was just trying to piss somebody off... it was simply part of a discussion. Same thing here. It isn't personal, it isn't with the intention of being belligerent, and I don't think any less of someone that likes Halo (Pyro, Keebs, and K-Man all do, and I think they're all pretty fucking nifty people, and I generally share similar taste in games with them anyway)... I just find the whole sense of division here interesting for a variety of reasons.
Maybe it just comes down to people wanting threads where the only posts within them are about the game itself as it relates to people who like it. Certainly not every thread has to be a discussion of the merits of one thing or another, and it would make sense that this might get on people's nerves when all they want to do is talk about what they liked with other people who liked it too. So I guess in that sense maybe I understand, but... maybe that just means we need a separate thread in these instances just for people who want to gush about something and talk about SuperAwesomeMoments A - F instead of whether or not somebody liked where the developers put the shotgun on level 42. Or something.