Just because it seems like an obvious question -- Why that particular type of "interesting"?
Yeah, I actually agree with that. I can spend a lifetime studying interesting things, and there will always be interesting things in the artificial world that I can study. Yet (this is just for me), there are few other things that can amaze me as much as parts of the biological world do.
The other thing I think about is this - what exactly is the stability of my terminal values? I've changed many of my terminal values over time, when I realized that I'd be happier without certain terminal values (e.g., deep ecology used to be one of my terminal values, but ...
It's an interesting question that I'm pondering.
Now, while I do question the intellectual honesty of this blog, I'll link to it anyways, since the evidence does seem interesting, at the very least: http://wattsupwiththat.com/2010/01/04/where-are-the-corpses/
http://wattsupwiththat.com/2011/05/19/species-extinction-hype-fundamentally-flawed/
It does seem that environmentalism can mimic some qualities of religion (I know, since I used to be an environmentalist myself). As such, it can cause many extremely intelligent people to reject evidence that goes against their worldview.
Furthermore, it's also possible that computational chemistry may soon be our primary agent for drug discovery, rather than discovering more biological compounds in certain ecosystems (that being said, drug discovery is entirely different from drug synthesis, and discovering a gene that codes for a particular protein and splicing it into an E Coli bacterium is going to be far easier than anything computational chemistry can do in the near future).
With that all being said, what now? I do believe that there is something of value that does get lost as habitat gets destroyed. But it's hard to quantify value in these cases. Certain animals, like crows, chimpanzees, orcas, and elephants, are cognitively advanced enough to have their own cultures. If one of their subcultures get destroyed (which can be done without a fullscale extinction), then is anything valuable that gets lost? (besides value for scientific research that has potential to be applicable elsewhere?) And is it more important to worry about these separate cultures, as compared to worrying about different subspecies of the same animal? Certainly, we're now beginning to discover novel social networks in dolphins and crows. But most of these animals are not at risk of extinction, and even the chimpanzees and bonobos will only get extinct in the wild (at the very worst). There are other less advanced animals that have a higher risk of permanent extinction.
What we're prone to systematically underestimating, of course, is the possible permanent loss of micro-organisms. And of novel biological structures (and networks) that may be contained within them.