I have one hit medium/high armour melee builds with my MW Pike and I have taken 5 hits to kill an archer in cloth armor. Pike is affected an incredible amount by speed bonus, 27p (24 unloomed lolwut) really isn't much unless you get the speed bonus right. The slower the weapon, the bigger the relative differences caused by movement speed.
As for the OP, this selective applying of realism is very convenient. Of course jumpstabbing with pikes is ridiculous, but so is ghosting through an extended pike or being able block every stab by leveling your weapon horizontally in front of you. Pikes were an OP death machine in real life, their reign only ended by guns. It's not like they are that OP ingame, I would like to see all them crappy 2h heroes have a shot at playing with the 300 length pike, I will laugh as they fail miserably. If a piker jumps away from you, you simply downblock.