For me sprint works since it makes movement more involved and less passive than on previous games. Having normal speed and sprint diversifies general gameplay, having two gears ideal for different situations instead of just one. Even simple moving from point A to point B has some variation and doesn't feel stagnated. Switching gears also gives you sense of speed. #immersion
Sprint isn't objectively good or bad for gameplay, it just makes it different. For example I don't have any problems with larger maps, since to me 4v4 is the least interesting and unoriginal part of Halo. 4v4 on small maps is as generic as online mp gets, and to me that's not where Halo's unique qualities shine through.
While we've only seen arena mp so far, H5 is still being developed singleplayer first and other modes second. No matter which you personally prefer, Halo campaign takes way more time and resources than mp.( Gears of War 3 used 75% of resources for campaign and co-op, rest was used to additional modes like horde and mp)
Majority of design choices are made sp first, mp is just an extension of sp in that regard.