Everyone did use DMRs in BF4 for a few months when they made them mag stronk. That’s not a good reason against what you are asking Im just reminiscing.
The bolt actions are in the game as a sniper rifle. What would snipers use if not bolt actions Bolt actions with scopes? That’s lame and takes away from the sniper role. If every class had access to bolt actions we would be back to snipers being good for nothing but bush-wookies.
The developers have to balance all these questions when they make a decision. They undoubtedly have thought about it more than you and I combined. They have conducted trials. The way they go with it is in our best interests.
If it does happen to fail because we all figure out some exploit rather than using it as intended they will fix it then. That is the beauty of online gaming. Lets all just take a deep breath and be happy about a new BF game rather than picking it to pieces before we even play it ourselves.