They've gone back to their roots on this. When I played BF2 it was like this. It wasn't till recently where there were certain weapons could cross classes. I would say they should let shotguns cross classes still because its such a niche weapon. But each class is going to play a definitive role. This will stop the all assault squads or 4 assault 1 support which was super OP in BF4 tbh. Assault was also the medic, which should have never been in the same class. The only reason I didn't run assault is because I was one of the only ones acting as a mobile SAM with my RPG. While it was mostly for fun, it really helped on the few maps choppers dominated on cap support like Zavod 311.
The glint makes total sense. Snipers will be most deadly in the rain and at night which will be at random. The fog will be limiting, and the day will give away their position at the cost of max range lethality. You wont be able to CQC recon anymore, unless you're a fantastic shot and its only 1v1. At least support class gets some love with their lack of weapon choice. Support keeps the same abilities in BF4 along with the engineers repair tool. I'm not quite sold on the LMGs yet unless the BAR makes an appearance as it was invented in 1918. If there is a BAR, DICE will do it justice and it will def be the reason I play Support.
One thing I really hope for is time appropriate loading screens. This was my absolute favorite in BFBC2: Vietnam.