I truly, truly abhore the "delve" format. I loathed it during 3.5, and I still loathe it now.
I've found it to be a real disconnect when trying to follow any sort of story or suggested plot within a module. It's a testament to Wolfgang Baur's talent that I liked 'Expedition to the Demonweb Pits' as much as I did, in spite of the awkward, annoying presence of the "delve" format.
I really wish they'd dropped it after its first uses in 3.5 and not returned to it.
I couldn't agree with you more. The delve format may be great for RPGA events, 1 shot games and as learning tool for newbie GM's. But as a GM who likes to tweak published adventures to fit in my campaigns, I find the delve format actually makes modules more difficult to use.