Why does Esoteric refuse to update its older models ?

Esoteric wants you to buy the new stuff! Capitalism: Out with the Old - In with the New!

newer is always better, always!

for someone... 🤔🤔🤔

The only manufacturer I recall offering upgraded models was Ayre. Right now Denefrips is offering an upgrade circuit board for their Terminator dac, but other than that?  I don't think it's a common practice, at least as far as I've seen.  Unless you are using "update" to mean "repair"?
That's an issue with several companies, often due to to the lack of parts.  I know Naim can service virtually everything they've ever made, which is kind of cool.  

Esoteric is constantly evolving. They dont even use DAC Chips anymore.  There is no money in upgrading which is why companies don't bother with it.  ESOTERIC is always changing ownership which doesn't help with consistency either. They are always chasing the next buck to keep the doors open and stay solvent