Let me see if I can't infuse a little history logic in this discussion if I may.
I agree that I've always had issues with how easy trip, disarm, and sunder were in 3E. They could make big bad guys look stupid and took away from the heroic clash feel of the fight in most cases. But I also had a historic problem.
Disarm is really a move developed in fencing. The fencing style of fighting developed after the middle ages.
1. With the introduction of cannons and primitive guns it no longer made sense to wear heavy armor (ala the late medieval knight) it just slowed you down and didn't provide any reasonable protection.
2. If your enemy is not wearing heavy armor there is no reason to use big heavy weapons. They're just slow. A quicker weapon makes more sense.
3. Light quick weapons led to the development of what we might call the fencing style of fighting, particularly in duels, where disarming a foe could humiliate him. You had no intention of killing him.
This style of fighting for me doesn't have the medieval feel because it was developed after the middle ages. So I've never liked it in my games. In the middle ages the best way to disarm a foe was to knock the weapon out of his hand with a vicious blow or cut off his hand.
Trip is something that would always be useful but not easy to do in combat. Thus something that happened by luck or someone really skilled at it.
Sundering of weapons was something that happened in combat all the time but not by choice as much as by chance. Weapons in the middle ages were made of iron, not steel, and breaking was a part of combat, thus a knight always carried more than one weapon.
Sundering shields, well, that was more a factor of the type of weapon your enemy was using and the durability of your shield.
Either way sundering was very difficult to do on purpose it was more a random part of combat.
Sorry for the long post. I teach history for a living.
