Nudge isn't broken and it adds a little bit more flavour to combat, the problem isn't even close to being as bad as you make out. My main is a hoplite and very very very rarely do I die to nudges, in fact very few people use them effectively or regularly enough to make it annoying, even if someone does get a decent nudge on me I can normally get my block up in time and if I can't, then kudos to them for fucking me up.
While warband/ cRPG doesn't try to be overly realistic if you think that irl 2 people vs 1 guy using a shield wouldn't try to get that shield off him by grabbing it or punching him in the face then you are plain wrong. At the moment you are plain inviting people to nudge you into oblivion because of the way you hold RMB and back away as opposed to swinging your sword like a mad fucker. As others have already suggested, your main playstyle is 1h/ shield thus giving you the most options for nudges, don't cry because you are not utilizing them effectively because it is a lot easier do than kicking. Lastly, it is poor build choice for a pure melee shielder to be dying in 1 hit.
To address your argument about it being un-counterable; so is HA for the normal infantryman, so is a group of 3 or more archers/ xbow, so is being ganked by 20 kill hungry lowlifes, so is being kicked... There are numerous things that will result in you getting your ass handed to you, that is cRPG.