"There are four things that make a theremin beautiful that can not be seen in modeling, like the sound." - oldtemecula
Says someone who doesn't know the first thing about DSP.
Doing things digitally means you're dealing with numbers rather than voltages, and if the numbers are large enough (resolution) and change often enough (sampling), the design process is almost identical to that of a continuous voltage circuit in analog hardware, and the results indistinguishable. The digital state-variable filter is a direct translation from the op-amp topology, etc.
"Theremin design is so much fun I think some engineer ego's want to spoil it because they can not figure it out."
Another thinly veiled jab at anyone (though it is actually quite targeted) taking a reasonable, rational approach. EE's are out to tear down this whole mysterious field that they are utterly blind to because they know too much. It takes a complete non-engineer to properly engineer a Theremin. It's absurd on its face, and is the sort of argument a crank might make.
Theremin himself had degrees from Military Engineering School, Graduate Electronic School for Officers, attained a military radio-engineer diploma, and graduated from Petrograd University. That didn't seem to hold him back from actually inventing the thing.
Try as they might, analog Theremin designers, regardless of their background (or lack of it), haven't been able to really crack the linearity nut, nor alter the basic sensitivity without further seriously negatively impacting linearity. These issues are almost trivial to completely correct digitally, as well as a whole host of other issues (mains hum pickup, field reversal past null, instantaneous pitch indication, etc.). And the sky's the limit on fun voices to play with, as there are myriad digital synthesis methods out there already worked out, many of them fairly easy to implement in minimal hardware / software.