Some of you may know sprint was cut from Halo 2. But if it hadn't been cut and made it into the game and stayed in subsequent titles, would halo still be halo?
^ Video of what was cut from halo 2, watch the segment with Dual SMG sprinting for a laugh.
If Bungie could have made it work, then it probably have been such a talking point today, but playing on maps like Warlock, Lockout, Midship, etc. with sprint would have completely changed the game. Sprint could have worked on other maps like Terminal, Headlong, and Zanzibar, but it would reduce the importance of vehicles, which were assault and transport vehicles.
However, sprint was cut for many reasons. We know many of them, like it reduced the importance of vehicles on maps like the Ghost and Warthog for transporting players because sprint would allow you to make up 5-10 seconds to get across the map. Map control would play a less important part like on Lockout, Ivory Tower, etc. Sprint would unbalance weapons like the Sword and Shotgun. And many more.
Halo 2 also used to have a single shot BR when zoomed. I am glad that never happened either.