I think this is one of those 80/20 rule things. In 4E, you can get rid of 80% of the problems with magic weapons and armor by simply limiting such weapons to the original D&D range of +1 to +3. (And if you want to make that roughly +1 per 4E tier in the treasure guidelines, fine.)
Sure, that breaks down at the margins. You can't give starting 4E characters +3 weapons without repercussions, and epic characters still stuck with +1 are hurting. However, 4E is fairly resilient to divergences from expected equipment even as is. Make the equipment cover a more narrow range, and it will only matter at the margins.
Plus, if you have a bit of a "math problem" at certain points in the system, but equipment with a low variance is at least semi-optional, it is
real easy for each campaign to "fix the math" by simply handing out better or worse equipment.
I didn't come up with this idea out of whole cloth by the way. I'd like to take credit for it, but all I did was look at how Rule Cyclopedia magic items typically worked in the system. It had some balance issues elsewhere (some of which later edtions fixed), but +N weapons and armor wasn't one of them.
Edit for cross-post discussion: Note, I'm not saying that early D&D was perfect, or perfect because of weapons. Rather, the point is that such weapons work better with the other 4E balance mechanisms and structure than either system works by itself.