Well, the thing is, Win32 itself is pretty outdated too. People just use Windows Forms and .NET for their GUIs now - or some other graphics framework. You can find Win32 books out there, actually, a lot, but none of them are GUI stuff, because, like I said, people just use easier frameworks to draw their GUI.
I found
Windows Via C/C++ really good, but it is pretty advanced and assumes you have a knowledge of Win32 already. But, it is only system programming, so just know that before buying it looking for GUI stuff. You can take a dive if you want into that if you want to -
http://www.amazon.com/Windows-via-Jeffrey-M-Richter/dp/0735624240/ref=sr_1_1?ie=UTF8&qid=1411829146&sr=8-1&keywords=windows+via+c+c%2B%2B
Another problem is Windows 8. With the new UI and "applications" thing on it, Microsoft had to update all of their frameworks or make new ones for it. You can find a "Windows App Development C# or C++" anywhere now.
And, Windows 9 is gonna be unveiled on September 30th, and I assume that they are gonna show DirectX 12 alongside it. That is why I am hesitant on learning Direct3d, because Dx12 is probably going to have a lot with it because of the new xbox power and UIs of Windows 9.
Anyway, I have a bad habit of lengthly posts, sorry about that.
tl;dr
Win32 for GUI development is outdated due to newer, faster frameworks out there. Windows 8 doesn't do it justice because of it's "metro" UI.