Honestly, I have to agree with this. There are so many more useful items this gen that implementing an item clause could really be worthwhile.
The only strategy I can really see this negatively affecting is full stall (and possibly semi stall) but it's something that people would have to play around (black sludge, sitrus berry if we change the singles format to level 50).
e: This would have the added benefit of making the singles metagame mirror wifi which would further erode the barrier between the two communities. I can't see a downside here.
Sitrus Berry is a flat 25% heal regardless of your HP, it's been this way since Gen 4 [And therefor Sitrus is superior on any pokemon unlikely to survive 4 turns.]