While I do agree about the lack of variation in marines but the rest honestly feels like somebody asking for the same ol' Halo games, whilst I do love the old Halo's (I go back and play them all the time!), there are reasons for why they took out things and added new ones:
- The Brutes were whipped out by the elites after Halo 3 (most of them). The surviving Brutes wouldn't want ANYTHING to do with the Elites.
- You have to remember, this is the last of the covenant, they're really just pirates and/or terrorists. They'd only be about 10% of the power they once had which explains: No Scarabs, and no Drones.
- This is a shield world to survive the Halo arrays fire: You wouldn't wear body armor just so you can stab yourself in the neck. So there would obviously be no flood.
- and as for odst. Having the ODST's there would have been a great misuse of resources, they already have so many Spartan 4's. Not to mention that most (if not all) S-4's ARE augmented ODSTs so there would be a lack of ODSTs (who are still ODSTs).
- also for:No Marines: You must remember this is a research and exploration vessel, NOT a military vessel. It was ment for a few purposes.
1) Explore
2) Research
3) Training S4's
4) (and from what I have heard) finding John-117
which wouldn't require much military help seeing as how they weren't expecting what they found (the prometheans and Pirates). And if that's not enough there are a lot of points for it effecting gameplay already said by others.
- Also there are memorable characters: Dr. Halsey (in the Spartan Ops), Laskey and even the spartan 4 ranking officer (sorry, her name slips my mind at the moment).
So in the end;
There is a reason for why all the things explained were put in and taken out.