First glad you are back using Windowblinds. At least there is something great to help with the ugly look of the newer OS.

As far as the Control buttons and any other buttons you are referring to. It's really up to the person making the WB. We could all make the same size larger buttons. It's my opinion that it is done for variety and change of appearance. Different people like different things hence so many different WB styles are available. Good question hope this helps.

I don't think anyone is skinning to XP anymore. For myself, I only skin to Win7 as that is what I use. In order for me to skin for Win8, I'd have to be using Win8 to verify the useability of the skin. I don't see that happening any time soon.

As Dave mentioned the button size is what the creator deems it to be. The frame caption size (height) plays into the consideration for button size as well. I want my buttons to fill the space appropriately. Then take into account that you'll be losing 4pixels with the maximized caption, makes those buttons even smaller. In other words, if my base caption is 31 pixels then the maximized frame will be 27 pixels with 4 transparent pixels at the top.