I think it really depends on how often you are here.

If you live here, like I do, seeing the newest is seeing everything . . because it has to go through newest at some point right?
But if you pop in less frequesntly the individual libraries make sense so you can see what you "missed".
I keep going to most popular even though I can almost always tell what's goin to be there a week after it passes through "Newest". I do have to admit to looking once in a while to find teh oldest "Most Popular" skins are (like Copperdeck and Mac OS Tiger [with only 2.5 stars] from 2005 and Cyberskin from 2004).