Part of me wonders how much the covers of things like the PHB are driven by marketing decisions, rather than design considerations. Not that they can't often be the same thing, just that it's kind of the same reason the Mass Effect 3 media all star the buzz-cut hyper-masculine Caucasian dude, even though you can create your own character who may not look anything like that. If thirteen year old boys see a big shiny book with a hooker and a spiky dragon man, that may be somehow demographically appealing in a way that, say, 3e's more "it looks like an old book!" style was not. Art (especially cover art) made for "who do we want to buy this?" considerations rather than "what do we want this to say?" considerations tends to be pretty bad because of that.
I think it's sort of the "judge a book by it's cover" crowd vs the "don't judge a book by it's cover" crowd. I definately agree that 4e was aimed much more at visual gamers than previous editions, and that's likely the reason for the change to a more visual-oriented cover as opposed to the "ooo I'm a mysterious tome!" design(which was neat, but some covers were insanely busy and I hated looking at them).
Again, the two can often be in synch, but the 4e PHB cover (and, indeed, some of the other 4e design choices) seems to have a disconnect with that.
Honestly this is pretty common in any edition, some covers are hit and miss, like the PHB1 cover.
The PHB2 cover
Still pulls off the "muscle man and hot chick" imagery, but she is not even slightly as much only for T&A as the PHB1 cover.
The PHB3 cover follows the same pattern of maintaining the "slim and dangerous chick and the big muscle-man brute" imagery, but again, we've still moved away from the shamless T&A of the PHB1.
The Dungeon Master's Guide's 1&2 both feature good 'ol Wayne again, though the first is of a dragon(something he
can actually draw well).
Of course, apparently Wayne can't keep his fingers off the T&A button, so we get a rehash of the "I'm posing for no other reason than to show off my lady lumps!"
At this point I'm beginning to see a pattern and the patten appears to be employing Wayne Reynolds.
Even if we jump outside of D&D to Wizard's golden goose MTG: we find that Wayne can apparently attach a very obvious pair of breasts to even the most armored characters he can imagine.
Why this chick who apparently needed more armor and spikes than a spiked-armor factory wanted to have her breasts hang out is a mystery only Wayne can answer.
I mean the list goes on, but over and over and over again the recurring problem seems to be less that Wizards is trying out a new marketing strategy, most of their imagery is pretty good in grabbing your attention and aiming for that fantasy shtick, but the T&A appears again and again in
only Wayne Reynolds' art. This problem is rehashed in just about everything he's done for Pathfinder as well.
