I must be the only one to vote yes.
Reason - it's two fold. For fluff, a longer reach does allow you to strike first - which in a way is faster than your opponent, and in truth, a polearm is stiffer and lighter than a sword, which flexes and has a lot of weight in the whole length, and not just at one end where pendulum motion actually helps you accelerate the tip. Whether it should remain at +2 for the entire combat is debatable - if not, then any model using a two-handed weapon should suffer -1 strength every round as it gets very tiring swinging anything heavy about for more than a few seconds. If not applying this limit to other forces, do not apply them here.
Second reason - it's a rules machanic. It makes it work different to hammers and swords. Complaining about a halberd when a sword makes you more immune to damage? I assume this is for parrying, yet a halbered can be used to block an attack too, and falchions would be far easier being the lightest of all. Whilst this isn't a reason in your fluff argument, it is a good point I believe that the other weapons and their rules are not matching up to fluff and reality either.
My personal opinion would be that the halberd was the default weapon with no bonus, and a sword was an upgrade option. Halberds were always the default weapon for years for grey knights.