The thing about instant thrust is, to be frank, bullshit.
While the polearms can hit with force earlier in the animation, if you try a right-on instathrust it's gonna glance. Period.
However, it is possible to get of a very fast (read: not instant) stab by turning, but then that is true for the other types of weapons aswell. Although, admittedly, some 2h need a tad increase of their stab damage to reduce the amount of random glancing.
But this complaining about hiltslashing and the thrustglance-to-swing techniques is also bullshit imo; they're not that hard to counter and it's nice to have some things to break the "block-attack-block"-pattern.
Also: Again, NO weapons should have polestun. It's just silly.