I think its pretty clear. The Orc gets to make an AoO (Battlemaster rule 3.4) at 2 or 3 hex range and then the Halfling (we assume was making a "Charge" or "Move and Attack") continues up into the Orc's shorts if the AoO hasn't stunned or otherwise disabled the Halfling. To prevent the Halfling from closing requires either "intimidation" or Hold at Bay. If the Orc has friends, one can hold at bay while the others attack using the weapon length advantage.
This is perfectly realistic. In battle, pike/spear formations have the advantage because they can attack with more than one rank of troops and are packed in tight (the second rank can use the weapon reach to get additional attacks in). Pike/spear formations are effective against charging cavalry because the horse is relatively vulnerable in that circumstance. Disciplined open order troops (think Romans vs Greeks) can break ranks move in close and disrupt the pikemen quite effectively (and they did). Once engaged Pikemen are particularly vulnerable to flanking attacks.
So a single person armed with a polearm had better kill or stun the sword armed foe on that first chance or its not going to be good. Open order foot troops would never use polearms for exactly that reason. Cavalry gets to do both - they make first attack using lances and spears, but after initial contact switch to swords/maces since its easy to carry extra weapons aplenty on a horse. Mongol heavy cavalry carried lance, shield, bow, arrows, sword and axe giving them maximum flexibility.
Polearms are for disciplined, armored formations that move as a block on the battlefield. Everybody else uses swords, clubs and axes.
Robin