I agree with this. I think the best thing they can do is to give the users as many options as possible to customize nearly every aspect of GUI:
Font size, type and color.
Button / Knob / Slider style, gradient, brightness, texture and color.
Border thickness, brightness and color.
Scrollbar type, size, brightness and color.
Background brightness and color on everything.
Maybe consider giving us the option to use custom skins, so a skin, theme or a GUI-wise setting can be shared among users.
I know it’s not an easy task, but I think there will be a higher chance of everyone being happy, if they have the power to customize the look of their own interface, instead of hoping that Steinberg will finally “get it right” this time. Otherwise Steinberg will just keep changing things (accidentally?) that look good to some users to something that looks worse to those same users.
In other words, it sounds like a gamble, when every GUI appearance decision, that can’t be customized by the user him/herself is outsourced to Steinberg.