This. BR starts destroys the sandbox making a lot of the weapons on the map seem unappealing to pick up. Why look for pick ups if you start off with an already viable weapon that's only outclassed by power weapons? AR starts is the best way to play Halo.
BR starts(or any other utility start) have never "destroyed" the sandbox. There has only been a small subsection of the sandbox that contained numerous boring redundant clone weapons that were bad at their jobs.
The weapons on the map need to be appealing on their own merits, not just be pure upgrades over spawning weapons. Auto starts, give or take short range pistol, only "work" when no one in the lobby knows what they are doing, otherwise games devolve in a one sided pub stomp where fresh respawns can't do anything about players with long ranged weapons and are helpless against close range oriented power weapons. Its hilariously easy to predict what a fresh respawn will do when they are stuck with close range weapon. Either A.) They stick to close range paths on the map, which makes it easy to predict where they will come from. or B.) They rush for the handful of range capable weapons on the map and their teammates are still stuck with nothing effectively resulting in a 3V4(at best) scenario.
Trying to take the BR(or whatever the resident precision weapon is) out of the equation doesn't make the sandbox better if it is still loaded with redundant clone weapons with nothing unique to offer. At best you end up with prettier light show of players running around spraying their assorted bullet hoses.