Is it possible to turn of the new tile background colours in the Windows 8.1 Update?
I don't want to use a third party app but I'd be okay with modifying the registry if it can get rid of these terrible colours.
I don't think there is a registry tweak for this, why not go for the third party tool ? things can get really easy if you consider ,
Stardock has recently released beta version of Decor8 to support windows 8.1, you can use this awesome tool to get rid of the custom colours of the tiles , here is a link which gives a tutorial and download outlet