Your issues lie with a fundamental problem Halo hasn't yet addressed since its inception, but starting players with SMGs/ARs would be going backwards.
Players should never spawn without a mid-ranged, headshot capable weapon that has a scope. They need to be able to assist teammates from range, ping snipers watching their spawns, and quickly jump back into the fight. The need to pick up a BR off of the map slows the game down and creates a myriad of other problems regardless of the skill of the teams.
But the fault lies in the way the sandbox treats automatic weapons. These are made to be entry-level spray-and-pray weapons that are easy to get kills with, and that's a big part of the problem. By design, they end up being vastly inferior to the precision weapons. IMO, it should be the opposite. Autos that are placed on the map should have an important and relevant advantage over the other weapons. ARs would have big magazines and give the player better camoflauge; Plasma Rifles would stun players; Brute/Forerunner weapons would leave sustained damage or do more damage when you have an overshield, and so on. By making them powerful, giving them unique traits, and reducing their aim assist and stability, they'll be desirable and take skill to use.
This way, we'd give players a capable utility weapon off of spawn - one that can still outpace these automatics and support you throughout the entire game if you so choose - and then we'd place competent autos on the map and treat them like mid-tier weapons, instead of something you just throw away when you find a BR. If you're going to pick up Camo, maybe you'd go pick up the AR for the increased camoflauge. If you've picked up Overshield, maybe you'll dual wield spikers to make use of those perks.
IMO, this increases the meta game, broadens the sandbox, and doesn't handicap people off of their spawn. The best part is, this was already in the game to an extent. The AR made your camo activate faster in Halo CE. CE's Plasma Rifle also had plasma stun, and Brute weapons did extra melee damage in Halo 3.
This guy gets it.
