Can we take a moment and talk a bit about what made the Prophet 12 so great? Im not the biggest synth wizard so it would be interessting for me to know your thoughts?
I feel the design is very simplistic, With one audio path with some branching at the delay and feedback. Also the ton of mod posibilities. Is the instrument so great only because of all the content it has, or are there some particular design characteristics that make it super special?
Id love to hear your thoughts 
What makes a Stradivarius great, they only have 4 strings?
Quality is not created by design alone, especially in synthesizers. It's about the sum of the parts. Or another way to say it is, to see why it has the quality it does, you have to account for ALL aspects of it's design, AND how they fit together.
First and foremost, the P12 *sounds* great, which is the main requirement for any musical instrument. It's also ridiculously flexible for a polyphonic analog synth with programmable memory (26 sources, 97 destinations, for TWO layers!); it's basically a 12-voice modular that you can save patches on, but despite it's depth, it's close to knob-per-function. It has a massive amount of timbral variety available just from the waveforms, tunings, AM & FM modulations, even before you hit the character or filter sections. You can use sync, wave mod and FM at the same time. It does 4op linear FM. The 2 assignable strips are both position and pressure sensitive, in addition to the 2 standard wheels and aftertouch, giving you 7 dimensions of performance modulation at any time. You can store programs in Playlists, which is a lifesaver for live performance. It sends changes as MIDI CCs as well as NRPNs, so you can sequence performances including changes to the control panel. And on and on.
All of these things add up to a true instrument that is crazy deep, yet fairly immediate to program (if you know what you're doing), makes it relatively easy to prepare for live performances, and gives you many expressive controls for articulating your own phrasings with your patches that simply aren't possible on other synths without additional external controllers (and that is IF they can even respond to those inputs).
There are plenty of other things to mention, but hopefully that helps you see why it's not just a simple ole "one audio path" synth.