ebook length

A few years back, when pitch a novel to an agent, one agent’s site had in his original paragraph, “Will consider only 85,000 word length and above.” Then a brief reason about that. Most other agencies accepted 65,000 word length works. These were all for “print” press submissions. And, was true for most small to medium and “indie” press editors too. I was surprised on buying a few “indie” print press titles, things of interest, a crime novel, a Vietnam memoir, that the books were fairly thin in dimension. I relaize that formatting, font and point size, lines per page all can be different. On analysis of these books that I referred, one had 37 lines per page, and another had 42 lines per page. The rough word count on each was between 80,000 and 82,000 words. On relection, I thought they were not easy to read, that the presses were cutting costs. It had me wondering how they would “look” as ebooks, and would they hold a reader. Does it make a difference?  I am reminded of the movie Amadeus, where the Austrian Crown asks Mozart to just delete a few notes from a work considered to have “too many notes.”  I know we must write for many types of  word or character length formats, be it Twitter, another form or newsletter column width and length. Yet, my question persists. Is there an optimum word length for ebooks?