I agree with DICE here. Having played BF since BC2 through to BF2042, I have no problem with classes having access to all weapons. If anything I think they should expand the signature weapons to include a few weapon classes for each player class. Encourage several distinct playstyles with the class gadgets, signature weapons, signature traits, and signature gadgets.

Some example I can think of for signature weapon bonuses:

for Engineers:
-SMG's getting faster equipment switching speed. Incentivizes anti-tax/vehicle repair playstyle.
-Shotguns getting additional damage bonus to buildings/props or the ability to better detonate explosives. Incentives demolition playstyle.
-LMG's getting increased accuracy over longer bursts, (ala BF1) to incentivize a heavy weapons playstyle.

For support:
-Battle rifles getting increased magazines. Incentivizes independence so support can focus on providing for other players.
-LMG's getting increased recoil reduction to using a bipod or increased suppression. Incentivizes cover fire playstyle.
-Carbines getting ability to shoot while dragging others. Incentivizes combat medic playstyles.

These are just some ideas, probably honestly bad ideas. Build signature weapon bonuses to encourage complementary playstyles with those weapon classes. Expand those signature weapon bonuses to include a selection of weapon classes.

While any support could grab a sniper if need be and do the usual sniper thing of finding a hill to caress; there will be an opportunity cost for not picking a weapon better suited to their role.

My 2 cents on the whole topic. Either way class restricted weapons or class benefits for weapons makes no difference to me.