You will note I said "speeding up the game" which is not the most basic and literal sense of sprinting = moving faster.
Sprint speeds up core game play because of the movement... true. But that's the point. People have to think faster, and do more, in a shorter period of time - which creates another layer of skill. The lack of sprint gives people ages to make decisions. It's why it's a nice addition in many people's mind.
Do people remember how fast Quake was? It was beloved in the day... and that fast movement didn't get the same hate that sprint does in Halo.
Halo is more about the individual encounter than Quake was though, in Quake you very much saw someone and blained them, it was twitch reflexes at its best. But a lot of the combat came down to seeing someone and blaining them, the action moved too fast for individual encounters to really play out . You didn't outthink your opponent as much as simply out aim them a lot of the time. Of course good movement and positioning was important, but less so than in Halo (I feel).
Reach was the slow end of that, individual encounters lacked skill because you had too much time, and armour abilities which just simplified those encounters. I hope it never goes that slow again either.
Fast based gameplay, where individual 'battles' can play out is the sweet spot in my opinion.
The pro's reactions seem pretty positive, but the odd mention of some things, like nades being like Reach's dampens my hype, so mixed feelings from the Pro's reactions for me.