See this is the age old hippy, tree hugging way of explaining how bad things are.
The first thing is, there are tons of recreational things to do in lots of different areas of the world.  If skiing had never been invented, those same people would drive their cars and fill another hobby.  They would travel across the US to fish, or hunt, or snowshoe.  Maybe something else, but they are going to do something, and going to need facilities to do that.  So actually considering is bad is just labeling anything is bad, but you need relative comparisons to other hobbies, and linking them to other parts then just the act makes everything worse and I think escapes the point.
As far as materials and outwear, lots of companies give back much more then the company that molds the steering wheel in your Tahoe.  The owner of patagonia< not particularly skiing but involved, is the second largest landowner in the world second only to ted turner.  All that land is refuge and protected. Other companies use bamboo cores, and environmentally friendly materials even though they cost more.  Some ski areas use alternative energy.  Many skiiers do carpool.  As far as the skiing itself, its very low impact on the environment.
So its not really they bad as opposed to those companies that created the computer your on or the light bulb in your room, or the socks on your feet.  You know how much manufacturing, water, and infastructure it take for you to take a shit?