It's not just Reason and Rebirth. Everyone has been following this type of design for over a decade. Eventually I just gave up. Even the best software in the recording industry is hopelessly designed to resemble a physical piece of gear and to be clicked with a mouse. It is mind-numbingly stupid.
At one point Digidesign had this lower end product called a 001. ProTools is of course an image of a recording console on the screen. On their second iteration of this product, the 002 I think it was, they released an actual pseudo-console with some tactile knobs. For a moment I thought maybe they were getting a clue. But I don't think things have changed much. Recording engineers are still pointing and clicking. It is close to impossible to automate. (Of course they think they are automating, but they haven't got any idea what true automation really is.)
Either no one at these companies understands how to use a command line and parsed configuration files or, less likely, they do know but they do not believe their customers could ever learn.
I concluded I am better off using snd(1) than waiting for the recording industry to figure out how computers work (i.e. to become proficient in the ways of UNIX). At least the guys in the lab at Stanford have got it right. You can even use Scheme.
To further elaborate, getting deep into nerdland here...
The fundamental mistake with Rebirth is the literal translation. For someone to choose Rebirth over the actual hardware, they likely do not own the hardware (for those actually bothering to read this, software doesn't sound quite like 20-year-old hardware, especially in this example). Therefore, there was little reason to mimic the odd limitations of the originals unrelated to sound or performance. The UI could have been more...I can't think of the word but "homunculus" comes to mind, that is, the knobs and interactive elements could have been larger, while retaining the visual aesthetic of the originals. The 303 could have benefitted (as with modern CPU upgrades to it) live note editing. Things like that. Maintaining weird, frustrating aspects of the originals, for the sake of appealing to people who probably never owned them, would be my #1 criticism.
Bad - screen-rendered knobs are awkward to work with using pointer oriented input (mouse, touch pad/screen, stylus).