Can't you do dodge hits manually with high speed? You can hit a slow monster and then back away so that the monster doesn't have time to strike the character. However if you stand in front of the monster tapping "5" it just means you are not utilizing your speed in conjunction with the DV. When you are surrounded you can't back away and thus you're not getting the advantage of high speed which is in keeping with your suggestion. That so-called "kiting" technique could be incorporated into the monster AI as well which in turn would be kinda cool.
However I do agree that being surrounded should decrease the defensive bonuses of shields and weapons.
I've actually lately thought about the fact that you can block any stroke no matter how powerful the monster in question is. I think there should a certain limit on how much damage a shield can absorb. I also think that shields shouldn't grant any PV since if the you fail to block a blow your shield wouldn't help decrease the damage you take.