I have a feeling that magic items may be more interesting sans modifier. Take away the plusses and minuses, and you get away a large part from the "magic item store" problem that many people have run into, and the stinginess inherent in the thought that multiple magic items will "ruin" campaign balance.
For example, imagine a Holy Avenger without its plusses; a sword that "merely" penetrates the defenses of magical evil creatures and is able to dispel magic. Or, one of my personal favorites, the Frost Brand. Minus its bonus to attack and damage, it would merely shine when freezing cold, possess the power to put out fires, and deal extra damage against hot creatures.
Of course, magic items are still sharper and more deadly than nonmagical ones, and they have a certain property that allows them to strike more often by virtue of being of superior balance or enchantment. It perhaps isn't too much to allow magical items to grant a blanket +1 to attack and damage, or maybe +2. Maybe even +1 to attack and +2 to damage?
The net effect should be to roughly equalize all the magical items, and to make properties more important than bonuses, such that situation and player preference is more important than superior bonus, and to make the game incapable of providing magical items that characters discard at the first opportunity upon finding a brand new magical item and the problems that brings to any sort of self-consistent gameworld.