I just got round to reading the Standard Bearer article in what is probably now at least a one month old WD (the one where WH was released). In it Jervis said about how they thought the rules from the previous edition were almost right and didn't need changing but that they'd gone for a new edition because they felt that the surrounding hobby topics were more important now than ever and so they wanted to group it all together.
Just a couple of issues I saw with that:
1) I've not played it, but it looks like there are some major changes: More brutal combat, reverting back to the old army structures, magic has changed to be more dangerous, etc
2) "We wanted to bundle more background and hobby stuff" could be a revision, not a new edition. I think it is really code for "we weren't selling enough rule books and so wanted to make everyone buy them again, because we're GW".
3) Hasn't the hobby always been important? They've tinkered with the style in various ways (like the temporary "lets get the kids in" brighter coloured and slightly lighter feeling period) but it has always been about models, painting, scenery and the background.
As a related point, from what I've read it looks like they're going back to the old "lets make it complex so that you might need a GM" days. Scenery with special rules once you enter it, including dangerous woods, weird rivers and hills that can kill you, plus terrain that can either poison you or bring back wounds? Sounds like it'll over-complicate matters!