I love the amount of flexibility provided by the palette-based themes and was surprised that we could easily tune the colors but had no control over the opacity level used in the disabled state. We have customers complaining that it's too faint (compare with MS label in attached screenshot) and it would be great if we could address this as easily as the rest of the theme colors.

Reason for declination: 
The XAML team has reviewed this feature request and we are closing it because it is already logged in our feedback portal: 
http://feedback.telerik.com/Project/143/Feedback/Details/139310-make-the-disabledopacity-a-dynamic-resource

You can vote for it and follow it to track its progress. Any additional information or requirements will be highly appreciated. You can add them to the item or contact us through the support ticketing system with details.