I'll add my voice to the chorus and say that I don't find 4e magic items inherently less interesting than 3e magic items, by and large. There are a few exceptions - notably in the "wondrous item" category that's declined since 2e - but I generally find them more interesting now. Simple +X items aren't the norm in 4e; they're pretty unusual. Weapons, armors, and amulets generally do a lot more than just adding a simple bonus. All too often, items in 3e would have to fill one of the Big Six, and few characters had much interesting stuff beyond that. 4e is in a better situation, here, at least IME.
Anyway, I think the missing design space is easier to fill than they'd expect. Let me lay it out...
The real problem isn't that some magic items will be more powerful than others. The real problem is the level/pricing/bonus assumptions. (For those few who aren't familiar with 4e's magic items, they're tiered in a 5-level cycle. Level 1, 6, 11, etc. are the simple +X items, and item abilities beyond that +X are effectively worth between 1 and 4 additional "levels", so right now there's no such thing as, say, a +1 item at level 6.)
So, for items like that necklace, you don't need to make a new kind of DM-only item (we have artifacts for that). Just open up the design space so that a weapon/armor/amulet ability can be worth 5 or more additional levels. I mean, if I have a +1 amulet that costs as much as a level 10 item, it can have a major effect and still remain balanced enough for players to buy or create it.
I don't think the situation is anywhere near as dire as the blogger presented. The design space is there; it just needs to be used.
-O