Like which options? I don't remember seeing any more options in Reach or 3 than there are in 4, except for the gametype-specific ones, which have been replaced with new ones to better suit the new game types.
Also note that while had some game types that H4 doesn't, like Invasion or VIP, Halo 4 also has its own unique gametypes, like Extraction, Dominion, Regicide, and Ricochet, each with their own customizable options.
Ahem:
Removed Game Modes since Reach:
Assault - All forms
1 Flag CTF
Neutral Flag CTF
Territories - All forms
Headhunter
Stockpile
Insane
Race
Invasion
Invasion Slayer, Bro Slayer, and other similar modes.
Important Options:
• Sprint cannot be removed in any game mode besides flood (zombies only). Issue for some classic competitive modes, flood, mini games, etc...
• Flood removes the option to let zombies hold other weapons, restricts armor abilities for zombies to a set of 3 predetermined ones or none at all, forces humans to be bright yellow-green, forces zombies to not have sprint.
• Flag cannot be dropped in CTF, auto pickup cannot be disabled, flagnum cannot be disabled. This changes tactics for CTF, making body spamming the flag usually more effective than anything else, making it less strategic.
• Removed custom power up, which was a key element in many mini games and infection maps.
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The new modes added were appreciated, as were player trait zones. Regardless, the amount of custom game options removed with Halo 4 far outweighs what was added and hurt a large portion of the existing community. I'm not even sure if I hit everything with that list. This is on top of other issues such as infinity ordnance, random drops, a few bad power weapons, certain items allowed in personal loadouts, and more.
I will say this for Halo 4 though. Halo 4 has a large number of issues, the biggest being what is listed above because it keeps us from fixing them in custom games, but it has made improvements and it plays MUCH more smoothly than the past games. I went back to Reach lately, and while it was nice to have the options and the simplicity the game felt much more clunky than Halo 4. Halo 4 is aggravating in many ways, but 343i did also do pretty well in some categories.