Soap Box Time:
I think the reason Movie Bob "over-thinks" the Halo game series, to use some of y'alls wording, is thats what he does. He's a movie critic he watches tons of movie and critiques them based on they themes, symbolisms, plot, and characters. Once you done analysis of stuff like that for so long its really hard to close that part of your brain for other things.
The closes two examples I can think of right now are My high School English Teacher and myself.
In High School my English Teacher was a huge Christian. She went to private college and (I think PH.D. but know) mastered in the studied comparative religion and lit. From this she has this idea that all of Western Culture literature has some slant on Christianity. So literally every story we read had this to do with Jesus dying for you sins, or this to do with why the devil temps people. From a kids point of view it was absolutely nuts to think that the Giver represents why God sent his son to earth to die for your sin and forgive you for all eternity. But thats what she read into it and looking back I can see her reasoning for it.
The other example is myself. I was doing research into science fiction literature and my professor had me a term paper about how there is a slant in literature that any deviation for the human norm is evil (Cyborgs, robots, zombies, bio-mechanical augmentation, and so on and so on). Well during the time I was writing that paper and for about half a semester afterward all I could see in anything I did was how this trope effected the characters in any story I watched/played/read(especially video games). Was it true? No. Did it seem believe able to me? Yes. Did my room mates think I was crazier than normal? Whoo boy did they ever.
Now that was just one semester on one trope. Imagine if my job was to look for the symbolism in every thing I did and judge it based on how well it fits into the story. I would see symbols and meanings everywhere, like the DaVinci Code.
Now am I saying Movie Bob should just be close minded when he plays video games? No by having that vast wealth of knowledge of tropes and symbolism that, in my opinion, that helps him give a better voice as to how/if a video game is art or if it is just drivel. And it is only by making these ties, as crazy as they maybe to the outside observer, that will help expand games from "just games" to a socially acceptable form of media and art.
Tl;DR:
Does Move Bob over think the symbolism and meanings behind Halo? Maybe but thats what he does for a living. He analyse media, judges it based on it literary and social values, and give his informed opinion to use the audience, the masses, the sheep.
Should he close his mind and not analyze it because its "just a game"? No, as extra credits pointed out thats one of the reason why video games are so looked down upon in society. He should be able to state his ideas just as you should have some means or ideas to defend his analysis of the subject. Thats what you do with art.
Soap Box Done