Disclaimer: I’m not a designer, nor do I play one on TV. But I’ve been through every generation of computer UI since the 80s as an intense user.
I’m generally more a fan of flat design vs skeuomorphic design, mostly because it allows for more efficient use of a given number of pixels.
But flat design does miss out on some emotional connection potential for users transitioning from a 3D environment like music hardware. This is still a thing for guitar players only now starting to get into software. A stompbox UI metaphor creates an emotional connection for anyone who’s in the process of abandoning their cherished pedalboard in favour of a DAW environment. And a recreated a Jupiter 8 or MemoryMoog visual holds much emotional appeal for many hardware synth enthusiasts. And many a grizzled studio cat, who is migrating from racks filled with audio processing gear feels emotionally connected to the visuals of the trademark knobs, sliders, buttons and switches they’ve been twiddling for decades.
I’m definitely not enthusiastic about overly low contrast designs. Even more so when working on a 4K screen in non-retina mode (in my case a 40" TV on my desk). Different areas of the large screen looking differently is a feature for me, not a bug. – It’s also an inclusivity/accessibility issue, since not everyone sees colors with the same degree of vividness. Of course, colour schemes can also be too visually noisy.
And I think one of the problems is that what’s visually too noisy vs. what’s too low contrast attracts widely different visual perceptions and resulting opinions. From color vision deficiency to tetrachromacy, we see things quite differently.
So for my particular (obviously highly subjective) sensibilities, your UI mockup example is too low contrast / too few colours, while the current Cubase 11 light blue area is maybe a little bit too high contrast. But I definitely like the contrasting black bands as obvious cues, that those areas are for user input .
The other thing I really appreciate in a UI, is when I can immediately tell sub-consciously even without reading any labels and preferably even without directly staring at the screen, which potential sub -window (or UI mode) I’m in. – That in turn means I don’t want a consistent look between different modes/windows.
Obviously UI skinning would be a great thing for Cubase, but I have no idea how realistic that is given so much of the code is quite old and there are probably quite a few entirely different generations of code in Cubase.
One last comment - I’m not sure, if the version of Cubase you’re currently looking at is even giving you the complete visual picture. Cubase Pro has quite a bit more functionality than the other versions.
For example, the left Inspector area for Cubase Pro is a rather complex beast in my configuration with two tabs at the top and two more at the bottom.