This thread has had me ask myself some fundamental questions and answer them.
Q: what do I think is a better thing - more people or less people in the outdoors?
A: I'd be selfish if I said less. I think more people, or a greater percentage of the population, getting outside is a good thing.
Q: but isn't overuse a problem?
A: Yes. Popular areas are getting hammered. We need people to go to more and different places. We also need people to reduce the intensity of their use. Hiking is fine. Littering and used TP prayer-flags and erosion and wildlife getting habituated to humans and then shot aren't.
Q: How can we address this?
A: Education, enforcement and infrastructure. We need to educate more people more effectively about proper backcountry etiquette. We need to give people more options for places to go - either by building more trails and huts and so on or by popularizing existing areas that aren't as popular. We need more infrastructure designed for heavy use - boardwalks not mud holes, tent pads not meadow camping, outhouses not "shit behind a bush" - in both parks and non-park areas. And we need enforcement of rules for people breaking them - littering and feeding animals and parking illegally and driving quads through off-trail meadows and all that. Overused areas may need permit or quota systems enforced the way they are for Lake O'hara, Bowron Lakes chain, and the WCT.
How can we get that? Join mountain clubs and get your voice heard. Write your politicians and letters to the editor. Volunteer to help out building trails and repairing trails and soon. Advocate for more tax dollars to be spent on recreation, but put up your time as well as your money. Be proactive and educate others through not only words but deeds. And videos and instagrams and blogs and tweets and CT posts.