You do not need Shield Bash most of the time
but when you do need it, you're going to be happy that it is there.
Do not ask SE to "reinvent" this skill, too.
Oath gauge is for mitigation and stuff. I'm, like, 1000% happy with that.
Shave some cooldown time off of Cover and that'd be cool. I loved Cover is SB. In ShB I hardly ever use it.