Smaller weapons
Interesting point that theoremtank brings up is that smaller weapons are not going to be chosen. I think it would be cool to have an offsetting increased accuracy or increased armor class (or both) for using the smaller weapon. In other words, why would a fighter ever take a shortsword that deals 1d6 and crits on 19-20. They've done a great job already of mixing up the weapons and damage already with die types, threat ranges, and reach. Clearly, there are two reasons that stand out right now: for weapon finesse bonuses or for two-weapon fighting. What if you could get a +1 to hit and +1 to AC when using a small or medium sized weapon? Hmmm...particularly more interesting at the lower levels now.
They used to offset these with weapon speeds, but now that's no longer. Maybe the smaller weapons give an initiative bonus? Then you could quickdraw the big boy?
As far as why I think it should stand, unchanged:
1) Not a problem unless Str +4 or greater
2) Very comparable with two weapon (and loses ground in places)
3) Helps to differentiate between "fighters" and non-fighters (rogue/cleric)
4) Gives more choices for combat folks...do I go with one hander and shield or two hander vs. this creature. Always good.
If you were going to make a change, I can appreciate the justification of making it one feat. Since it is comparable to two-weapon fighting, and this can cost you several feats.
On that topic, if you have a problem with high end damage dealers, break down power attack into 3 point or 5 point increments and require more than one feat be taken to reap the full benefits of this damage dealer!