I don't think that is the reason. But it could fit in with the humans being human thing.
Basically the humans find stuff, kill it, take it over, advance their technology...repeat.
I will go to school. Then proceed to get bored during the week and just mess around on the computer and watch TV. Then on the weekends I will go to work and then play Battlefield 3, Minecraft, or Counter Strike.
I think it would be cool if your Spartan fell to the ground when killed. And instead of respawning it would show him shaking and stuff then transforming into a flood thingy.
Humans are the biggest threat simply because we are humans not because we did anything. We believe ourselves superior to everything and don't care what we do to all the inferior things. So with mentality like that the Mantle is surely in danger (that is what the Didact would think I assume)
It's also just advertisement so that when you buy your Mountain Dew you also get a nice bonus to keep you as a customer, or it will make you grab Mountain Dew in the split second decision to grab a drink.
When you are emptying your wallet and shoving it all down your face for Halo then there is most likely another problem at hand.
I don't know, but in an interview Cameron got pissed and basically said it is okay for him to borrow some ideas for Halo as bungie used some ideas from him.
If it makes you feel better I'm about 50/50 on the multiplayer. But this is cause I'm not that big a fan of Halo multiplayer. After I say that though I won't be off the multiplayer ever.
For Campaign and Spartan Ops I'd say about a 9.
For multiplayer about a 5.
And the community is going to be garbage like usual except those really dedicated fans (forum goers).
Elites are actually based off of the aliens in the aliens series.
There are several things Halo has taken from aliens and bungie admitted this. It also pisses James Cameron off when people say Avatar stole ideas from Halo.