The problem with each album is incoherence and a feeling of inconsequentiality within their discography. This is probably because both preceding albums (In Rainbows and Merriweather) felt like epiphanies, as if all the envelopes they'd been pushing recently had just fallen into place. I think both KOL and CHZ are great, but you could never call them their best work (even though my gf thinks CHZ is their best album haha).
Yeah, I agree with what you're saying, I just think that flaw about them lowers the ratings on both those albums lower than a 4/5 lol. I give an album a 3.5/5 is it's a great album with some minor noticeable flaws that make it uneven. I give an album a 4/5 if it's a solid release with really nothing wrong with it other than it not pushing any boundaries for the band or music in general.
I guess despite agreeing on the albums and their qualities we just have different ideas when it comes to grading. I still get a huge kick out of each album, and find them both full of awesome sounds and ideas, even if those sounds and ideas aren't exactly arranged meticulously or new to the band's canon or anything.