People (pole users) will say it's a feature, and that it's the most natural thing in the world, but actually it's a pain in the arse, and I see no real reason why a poleaxe or a spear should stun you more than a sword or a greatsword...
Let's take a look at polearms for a second, shall we? There are axes which deal a lot of damage and break shields easily, there are long spears perfect against cavalry, and there are some which have even a longer reach than greatswords, like the glaive.
Then there's polestun, which makes no sense - at all.
Remove it already!