Would it just break the game or something? We can only use three weapon sets to begin with, and one of them (pistol/shield, arguably dual pistol as well) is such low DPS that it is nearly unfeasible to use on its own. Our AoE kits mostly make up for this drop in damage, but to the point where using your own personal and stat-wielding weapon is potentially worse, and makes builds limited.
I admit I can’t speak for PVP balance, but considering the madness that certain other classes can pull, blocking once with a shield on a long cooldown hardly seems unfair.
I really love the rifle skills. All of them are actually useful and the auto-attack even pierces, but it’d be nice if I could actually use a shield without being mostly useless. Getting weapon swap probably won’t happen, but it’d be a much more fun class if it did.