> Why would the years of life on earth (or evolution) matter for species alive today being of "ecological importance" or not?
It matters because we're not that smart. A species deemed "inessential" to ecological importance might very well turn out to be critical for unforeseen, even unforeseeable reasons. Not just to the species itself, which you seem to discount despite their ancient pedigree, but even to us through second order effects.
The amount of time a species has been around is a strong clue that they're fulfilling a role in the ecosystem. Nature doesn't really do 'superfluous'; everything connects. Not in a hippy dippy way, but in the realest way, and in ways beyond our comprehension. The classic examples when I was growing up of 'nature being wasteful' - the appendix and 'junk DNA' - have now been revised... Because we learned more.
No one knew how wolves change rivers [0] until it was studied. In hindsight it's obvious and makes perfect sense, but we didn't deem wolves "essential" when we killed them all.
>It matters because we don't know so much. A species deemed "inessential" to ecological importance might very well turn out to be critical for unforeseen, even unforeseeable reasons
Sure, but that's an argument for "evolution being so complex and long process, we don't know much about which species is essential or not".
Not for the original claim "After billions of years how many species are not of ecological importance? Maybe some primates?" which seems to imply that all/most specific are of ecological importance just because they're old, except maybe some more recent ones like primates.
The two claims are basically saying the same thing. You can't deny one and not the other.
Evolution has taken place over billions and billions of years in a system that's far beyond our comprehension in complexity.
Evolving - or even not evolving - in this system over billions of years and surviving implies importance. I can't say it guarantees that a species is "essential", but that was never the argument.
It matters because we're not that smart. A species deemed "inessential" to ecological importance might very well turn out to be critical for unforeseen, even unforeseeable reasons. Not just to the species itself, which you seem to discount despite their ancient pedigree, but even to us through second order effects.
The amount of time a species has been around is a strong clue that they're fulfilling a role in the ecosystem. Nature doesn't really do 'superfluous'; everything connects. Not in a hippy dippy way, but in the realest way, and in ways beyond our comprehension. The classic examples when I was growing up of 'nature being wasteful' - the appendix and 'junk DNA' - have now been revised... Because we learned more.
No one knew how wolves change rivers [0] until it was studied. In hindsight it's obvious and makes perfect sense, but we didn't deem wolves "essential" when we killed them all.
0 - https://www.youtube.com/watch?v=W88Sact1kws