There is a side to this challenge that is not so feature dependent. TBH I am glad 4 is taking a bit because it gave me a year to try to understand so much of what is already here. IMO much of the joy of synthesis is in comprehending what is going on to some degree (and I do get it wrong often). I really appreciate that I could probably just turn to FM/PM synthesis, for example, and remain totally interested experimenting all day, because we have all the tools here. It is nice to continually return to these different elements, just as it is exciting to think that we will bring things like full-fledged wavetable synthesis or sampling into the fold, as we move forward.
Another positive aspect is that the principles of synthesis are universal. So you could desire a certain synth, but then relax, learn that type of sythesis in Audluus, then when the price drops and used units come up, it will be like you were working with that piece of gear for a while. It almost seems to balance excessive consumer desire with technical competence. It appears to slow down the hurry to buy, and encourages a decade-wide view of what is available. I found that once I had a few key pieces, I could admire all of the new gear but have a nice calm pace of interest where the acquisition of tools includes significant gratitude for innovation even if you are not looking to buy what you are admiring.
One could open up Ableton and arrange a bunch of loops and samples, which is fun. But to get Audulus to make dramatic patch changes that sound as though you are producing in a DAW, I believe, makes for a good logical challenge.
Regarding presets, it’s nice to have a bank of settings that display the range of sound possible – presets that follow the module or set of modules (this is probably where semi-modular approaches could be better because then you have one complete object, that includes multiple components, but with an overarching list of settings).
So, in terms of simulation, the idea of producing a logical system using and/or/if/then/etc., that governs the oscillators, envelopes and whatnot is almost a different concern. In this case, the user almost just needs to work with meta-logical approaches, which require more brain power. Although I do like when some of this gets grouped into a module so that there is a layer of interaction on the front end which is fluid and efficient to work with, there is still something unique to modular synthesis in terms of modulation, that can itself get lost with a digital preset feature.
Perhaps one of my favourite related outcomes is I just love brewing up a hot cup of coffee and watching some of the youtubers who are constantly working with new gear, then getting excited and opening up Audulus. I feel like this is actually a goal lots of people kind of desire. For example, I ordered a kit guitar from China. Part for part it is a piece of junk. I think maybe it came from a pile of “b” or “c” grade Q.C. rejects. But the fact that I had to assemble it and solder the pickups to the pots and all that, almost opened up the instrument to me for the first time.
So the $3000 guitar or the $700 euro module can be so exiting and otherworldly to acquire, but that type of excitement is fleeting. One almost has to be disciplined to transfer that positivity into some sort of mastery before it slips through the hands, so to speak.
Finally, I would say that really the sense of community, sharing, and good natured technical collaboration (engineering), seems to be a refreshing way for people to work together. It reminds me of carpentry books from the 70’s. 
Audulus is a great way to experiment with a wide variety of synthesis techniques and effects without breaking the bank or filling up the studio. BTW my current iPad Air 2 has developed a malfunctioning home button, so I was forced to buy a new iPad Air. A pro was really overkill for me since I primarily use the iMac, but it’ll be nice to have a bit more horsepower. My old one still works more or less so I can potentially run 2 iPads and an iPhone with Audulus. There might be something interesting one could do with multiple devices. Hope Ableton link is included in the next release.