I don't know where the whole "Halo needs to be rated M for it to be a good game" thing came from, but it's a wild theory.
Also, I'm pretty sure if you did a quick forums search, you'd find at least one other topic with this same theme - might just want to commiserate there.
Pray tell how is it possible to have the more mature themes of Halo on a T rating? How can the flood exist and not be neutered? How can you show of Zeta Halo properly? How can you give the marines that light bad language that gave them character?
How on earth can you have the horror elements of the franchise appear on a T? Palace of Pain? Imagine how awful and disappointing it would be for things like that to be included in a watered down way just to aim for a lower rating. Extremely sad
Any decision that is made to take away from the game purely to get a T rating is a bad choice. The M related parts of Halo gave it some of it's character.
Something as simple as blood splatter just makes combat more satisfying. Is it essential? No. Does it make the game a little better and more fun? Sure! Who doesn't like tearing through enemies and seeing the result of their destruction? Removal of small things like this makes the game worse for no good reason
"Mature themes?" What are you talking about? There are PLENTY of mature themes in T rated games. HELL, The Sims is rated T and you can do ALL KINDS of mature stuff in The Sims.
The flood existed in HW2 - that was Teen.
Marines "light bad language"? Have you ever been around a marine, or an ex-marine? The stuff that comes out of their mouth in M Halo games is baby talk compared to what real marines say. It doesn't matter if the marine in the game tells someone to "go to hell" or "go to heck", because either way, it's the child version of what an actual marine says.
You can still have horror elements in a T rated game. Have you played Alan Wake? That's a T game, and still has amazing horror elements.
I agree with the blood splatter element, I think that gives the game added fun in a comical manner (not realistic at all though).
Halo fans just seem to want to find the most minuscule thing to whine and complain about before the game even comes to fruition, or has even been fully showcased. The fan base is so embarrassingly entitled anymore, that things like an ESRB rating make them take up arms against a franchise.