It’s not flat for the sake of being flat. It’s easier on the eyes in a professional environment. Also, I don’t take “flat” design religiously. Make something beautiful, functional and elegant, and I wont have a problem with it. Look at UAD visual design. It’s great.
You can’t say the gradient mess of Cubase was not due to some technological limitation. Computers are insanely powerful now, and we need to catch up. Also waveforms–they look like this because of performance limitations of the past. Look at Pro Tools metering–and then look at Cubase’s gradient mush. Then look at any professional mixing console and outboard gear. In fact, look at Steinberg’s own flagship interface’s hardware and software design: AXR4. Then look at Cubase’s gradient metering.
So yeah. Things have room to and can be improved. Look at Wavelab 10! It has improved so much.