themes should have tokens for elements, not colour shades
At the moment themes try to recolour SharePoint by replacing colour shades. Since 2007, customers rebranded SharePoint using their own brand colours and graphics designers yet at the moment we are forced to replace the colour shades a designer at Microsoft came up. Every time I attempt to use a customer's pallette, the result is overuse of one colour.
Tokens should be granular like web part title, web part background, site heading, navigation text etc.