I think reducing PS isn't a good idea. Personally I'd like the dev's to leave this kind of thing alone until they perfect other areas of the game (that are not related to balance), and maybe tried to make strategus into a decent game.
But if I was to suggest a balance, I'd have to agree that Strength builds (for infantry melee) are far superior to agility builds. Which makes pretty good sense.
In an ideal world agility would be like in many games, where the more agility you have, the more you can swing without having to 'rest'. Also if riding skill actually made a noticeable difference when riding horses agility wouldn't be strength's little red headed step child. If you didn't get free WPF on every level, and actually made it worthwhile/necessary to use the Weapon Master skill, then it would help the imbalance between str and agi.