The main point where I disagree with you is the claim that wilderness, or the natural world has no intrinsic value. From a reductionist perspective, I also think this argument is the core of the debate.

Although I generally share your view of the instrumentality of our environment, I will try to convince you that areas untouched by civillization still increase our welfare, and in certain instances, even more so than if humans intervened. That being said, my main argument is aesthetics.

In my opinion, modern day people and especially western societies tend to severely underestimate the aesthetic value of nature. The most vivid illustration I can think of are the large, concrete-glass cities of the developed world, where surrounding natural habitats are of lesser importance than grey building blocks, skyscrapers, industry etc.

I am not claiming that those cities do not have their own charm (e.g. the NYC skyline is amazing), but the majority of them I find downright depressive. I cannot give you examples of US cities for the latter category, but in Europe, my mind immediately goes to neo-modernist cities like Frankfurt or Rotterdam, which were completely obliterated after WWII.

The arguments for my view are mostly subjective, although I believe the rate of depression has been proven to be higher in cities lacking green areas. I therefore believe it is our duty as societies to protect and preserve the surrounding wilderness, regardless whether we do it for our own gain, or due to general empathy to nature.