I can't answer much to gradients or things like that (I just don't have the eye....so I'm not going to get into the weeds on that), but I would imagine the iWork icons being unchanged has more to do with the fact that, by all accounts, there are new versions of iWork being released this fall and those new icons haven't been previously shown to the public. All of the other icons have been shown numerous times, whether at the WWDC keynote or in the various builds of iOS 7. So far, the new version of iWork has been kept under wraps.
Add in that the iWork site in question is a beta site meant for devs, and I would think that we shouldn't rush too far too judge something for which we don't yet have all of the details.