if that's the case, IMO it would have been better for them to simply drop the d20 logo and make the book stand alone, a la Mutants & Masterminds, Arcana Unearthed, and others.
what's the point of attempting to convey compatibility (which stating the PHB is required does) if there is no compatibility? why require another book if you're only going to need three pages out of it?
White Wolf obviously doesn't need the d20 logo to boost sales for these books. not only does White Wolf in general and these games in particular already have wide name recognition in the RPG community, but the sales of the afore-mentioned M&M and AU prove that OGL games without the d20 logo can sell just as well or better than those with the logo.