Mustrum_Ridcully
Legend
I am not sure "defining" is the right work - unless I think in terms of "muscle definition" - Most of the cruicial items where just giving you plusses that would somehow affect your ability to hit and deal damage or avoid or survive damage. And not in any particular interesting way, just by increasing your numbers.They can now achieve a lot of the effects without dependence on magic items which is a good thing in my opinion. In 3rd Ed particular a character was as defined by his items as much as anything else.
(A very simple example of interesting might be more an example like Boots of Flying - you can fly so you can deal damage to other flying opponents, or you can fly to avoid taking damage. But it's "interesting" because these uses are more open ended. Just adding +2 to Strength to get a +1 to attack and damage isn't interesting.)
Of course, 4E didn't entire eliminate this, but at least its not hidden behind ability enhancement and stuff like that, its straigtforward "this adds to attack and damage, this adds to AC and this adds to other defenses). Still boring, but at least without the fiddliness.