Why doesn't Microsoft allow unsigned visual styles?

[flarn2006]

As we all probably know, uxtheme.dll (the DLL which manages visual styles) doesn't allow styles not made by Microsoft to be used. Does anybody know why this is? I know there's a patch available, but I'm just curious. Why doesn't Microsoft want us using third-party visual styles?

[ccl0]

my guess is they dont want anyone altering and of the os files.

[PC_LOAD_LETTER]

they just really like the color blue.

I don't think an official statement has ever been made as to why themes are so locked down but if i had to guess its probably a marketing decision. They dont want to 'dilute the image' or some similar marketing nonsense. I think they underestimated how many people would adopt a skinned interface which is prolly why it looks like it was designed by Fisher-Price. Its kinda sad when the shiny translucent, color changing Aero glass in Vista comes off looking more professional than XP's "Bliss" abomination.