To be fair, the two (JT to AB and HTDAAB to new album) aren't quite direct comparisons. Even U2 members say it is only similar. I feel the comment was more about the mood.
Plus, we can't overinterpret as times have shifted too much.
As we all know, in 1991, we didn't really have the 'net (at least in terms of how it exists now). So information didn't travel that quickly. If today's technology existed then, perhaps we would have heard a lot about U2's "new sound" and "new look".
Also, the time between R&H (which did have 9 new songs, and new b-side material) and AB was 3 years. We are now moving to 4+ years since HTDAAB. Furthermore, the time between JT and R&H was only 1.5 years. So while U2 clearly were slowing down already at that time, in the midst of arguably their largest popularity, 3 albums were released in 4.5 years, with a movie! In contrast, there have only been 2 U2 albums of new material released since 2000, so clearly people are wondering what's going on. As such, U2 has to justify the delay.
Going back to what is arguably the height of their popularity, U2 didn't really need to talk about these changes - U2 knew they would sell. JT and R&H sold millions. MTV still played videos and radio still played songs from all sorts of artists (not just a pre-selected group of 20). So U2 didn't really need to advertise that much - they were able to go with it.
Lastly, in 1991, I think U2 wanted to surprise the world. While the transition from "War" to UF may have surprised some, the sound shift wasn't nearly as dramatic as JT to AB. More importantly, though, was the image shift. In the 80's, we saw U2 grow up. Bono's hair was a reflection of the times as well (from punkish mess, to mullet to long hair). 1991 had U2's look and sound change and I think U2 wanted that on the "down low" until the album was released. In contrast, come 2009, fans are used to U2 changing their looks, sound and style. Hence, it won't be a shock any more. In fact, people expect it (kind of like they way people wonder what Madonna's new look will be on any album). So Edge's statements are merely reaffirming that a change is coming.
My guess in all of this is that there will be songs that could have fit on prior U2 albums. After all, songs like "One" and "Stay" could have fit on previous U2 albums. But there will also be songs that are radically different - and those are key. On R&H, we started hearing songs that indicated a potential shift (like "God Part II"). We also heard those types of songs on HTDAAB (with "Fast Cars" and "Love and Peace"). So it will be interesting to see where the new work takes us. But I won't be surprised to hear some songs that are more "traditional" U2.