I'm not so sure it is about logic. My understanding, and this is just from what I've read about it, is that it wasn't working out exactly as they wanted it to but the changes they want to make will require more time than is needed to get the rest of 5.2 up. So, instead of making us wait longer for 5.2, they are pushing item upgrades back to see if they can get them where they'd like them to be.
I was under the impression item upgrades were gone until 5.3 at the earliest. Unless you have information that proves me wrong, I'm standing by my original statement of "this is a lazy solution so developers don't have to solve this problem."
I have an extremely hard time believing that filtering out items above a specific item level is a difficult thing to manage. They seem to do just fine filtering out items below a certain item level.
Also, RE: The idea that disabling item upgrades across the board makes decisions easier for people. It doesn't, anyone at Blizzard that believes it does is deluding themselves.
I'm not entirely sure where I lost ya.
I know they are hoping to get them back in 5.3. What I was saying is that they are having problems getting them to work how they want them to. Rather than delaying 5.2 to tweak it further, they are pulling it out and going ahead with 5.2 without it. This gives them time to keep working on it without making us wait for content that is ready to go.