Knock Down: Getting up and attacking

A situation came up this weekend where one of the players knocked down an enemy combatant. It seems that on his turn, the enemy combatant can get up (instead of moving) and attack (p.109). That doesn’t seem to give any real advantage to attempting to knock down an opponent in the first place, unless you have several allies, and even then, the combatant can just get up in the midst of them without hindrance. Unsure of how it’s supposed to play out, I ruled that when being attacked by an enemy, a prone combatant could attempt a new save vs. Paralysis on subsequent rounds to get up (and subsequently attack), with a -1 penalty to the throw for each attacking combatant after the 1st, (which seemed reasonable at the time, as the PCs, in the following 2 rounds, swarmed the fallen enemy with 3 and then 4 of their number). How is it actually intended?

This is discussed at length here:

Thanks Alex!