Every of that technologies are under continued development. Why the eco-solvent inks have switched to a second generation in 2003, a third in 2006, a forth last year and so on? Do you know the improvements Roland have made with the Soljet Pro III (2006) because of known issues with the Pro II (2001)? Printhead drive system, Ink supply and so on? Why we don't print with Epson DX2-heads anymore in our Rolands, Mimakis and Mutohs? Why Roland have introduced a Soljet Pro IV in 2012? Have you ever read a firmware revision record of a well known, popular model from Roland or Mutoh for example? Summas S-Classes are proven technology since 2005, but they are now at firmware version 39, the last revision is from 2014 (9 years after introduction). The next generation S-Class2, introduced in early 2013, is on firmware revision 17.
No company, if its name is Roland, Mutoh or HP, closes down R & D just because they have successfully developed one printer model. Of course they check feedback from the market and try to improve their products, and we should be grateful for that. A lot of people using their L25500 since years, and they are happy ... but of course the second generation have improvements, as the third generation too.
Using heat to create a layer of latex polymeres with embedded pigments is the basic technology which works since 2008, with the advantages over eco-solvent like immediate drying, more scratch resistance, water-based and better results on
paper and textiles than eco-solvent. Todays latex printers have even more scratch resistance, higher printing speeds, faster heating and so on, and improvements in user interface, colour management and much more ... not a single innovation to blame them for.