As to why, the Saunterer would like to quote himself (from The Life of the Creative Spirit, p. 151):
A naturalist is someone who, in sensing parts of nature with a mind trained in biology and ecology, and a heart trained in beauty, senses beyond the parts to a transcendental kingdom, the spirit of nature. A John Muir naturalist, beside being a naturalist, has John Muir’s fight to see that wild nature is abundantly and perpetually preserved, sustenance for spiritual well-being, where nothing ever goes tiring or disappointing or betrays itself by a false note.
It is pointless to talk of protecting nature without specifying a purpose. One purpose will require one type and extent of protection; another, another. Of the two reasons for preserving nature for our physical well-being - as, clean air and water, and medical drugs - it means nothing if nature is scarred, or if there is no solitude, a billboard on every tree, loudspeakers by the streambanks, traces of human activity everywhere. But of the reasons for preserving nature for our spiritual well-being - connecting us closely to God, benefitting our creating, and cleansing us of our troubles - it means everything.
Although most environmentalists and conservationists are for preserving nature, that is their secondary concern. Environmentalists are primarily concerned with keeping the earth safe for our health, and conservationists with knowing how much of nature may be skimmed without endangering its ability to renew itself. If environmentalists succeed, the earth will not be a dumping ground for pollutants. If conservationists succeed, we won’t run low on good topsoil, water, and plants and animals important to commerce. Yet their successes may come in ways that fail to keep the spirituality of nature alive. That duty falls to John Muir naturalists, those with John Muir’s beliefs, as extracted from his collected writings and applied to today.