What? Modern "good interface design" (at least by HN standards) has almost nothing to say about complicated 1000+ feature apps. (In fact every time I rant that modern design sucks and that apps need more features the first response I usually get back is, "but that's so much more testing! Do you know how many execution paths we'd have to manage???" Well, that is kind of the point)
Have you ever produced music with any of these tools? For one, their goals are different -- FLStudio, for example, tries to be "the fastest path from your brain to your speakers", and the interface seems as such and is loved for it. Ableton intentionally crams everything into one screen because it is used as a performance tool -- if you've seen any recent photos of Daft Punk et al performing, you'll see it running right there on a laptop, usually above the mixer or the CDJs. Cubase has kept an interface very similar to its original Atari 2600 (I think?) version, because people have been using that app for 30+ years now.
Any time I see new-school UI designers' take on audio apps I cannot help but cringe. They are completely misunderstanding and underestimating their audience -- audio is complicated and we need complex tools to do what we do.