Why does Esoteric refuse to update its older models ?

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 

@jasonbourne52 that is not capitalism  it is consumerism and psychology. Under standing your customer and their desire and willingness to pay big $$$$$$ for the latest and greatest. 
As @riaa—-blah blah blah said there is no $$$$ in up dates unless the upgrades are modules (Simaudio/NAD) that you are selling hardware for $$$$ and you get your customer back in the Stereo Studio. 

chayro

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 ...

I think the practice of a manufacturer updating equipment is more the exception than the rule. ARC is especially noted for being willing to update older components.

@riaa_award_Collectors,

Esoteric has been a subsidy of Teac Corp for over 40+ years.  They do NOT change ownership.  Perhaps you are referring to distributors?