Prophet X also has 8 voice polyphony - when using stereo samples - and from what I recall, is bi-timbral at most. The much steeper price makes it a harder sell.
The Prophet X’s cost is partly rooted in the hybrid design, and partly in the absurd amount of storage for samples. Thankfully SSD prices are dropping rapidly so that can and does change over time. The polyphony limits are due to the sixteen analog filters. I’m willing to cut hybrid instruments more slack in the polyphony department for this reason, presuming their filters speak to me (and even there you have some flexibility - in sixteen voice mode with only one filter per voice you can maintain the stereo image for a sample by bypassing the filter, and in thirty-two voice mode a single pair of filters is used paraphonically.) There was always something special about taking samples and running them through a good filter which is an itch that instrument scratches nicely for me. Obviously everyone’s needs, tastes, and budget will lead them to what works best for them.
I think if ASM put 8 analog filters, you're not looking at a $700 desktop/$1300 keyboard Hydrasynth anymore. Novation Peak (a desktop) goes for $1300, so maybe it'd be a $600 price increase for the customer?
Hydrasynth has 11 filter types to choose from, so I would assume going w/ analog filters over digital would compromise that flexibility as well.
On Elektronauts, one of the very first response on the Hydrasynth thread was "I’ve concluded the price tag is fair compared to what I would have to pay for a mouser cart of components; designing, testing and minting my own pcbs; custom steel case; all that DSP programming, assembly and GUI OS." Perhaps that is what Theo is thinking about - implementing a softsynth on regular PC then porting it to custom hardware. He could probably do it if it's strictly a box just to run the software - no keybed, no ribbon controller no knobs, etc. However if he wants to add a keybed, knobs, display, etc. I think it would be difficult, if not impossible, for him to build his own Hydrasynth, complete with polyphonic aftertouch keyboard, while keeping the cost as low as ASM has managed, thanks to the practically in-house access to keybeds, chip fabricators, etc.
Blows my mind ASM did the firmware in assembly language.