Walking around busy temples and stuff can be pretty hard because people don't want anyone else in their photo. It has to look like they just chanced upon this ancient temple in the jungle, rather than getting a minibus there with 20 other people.
Sometimes the more savvy local tour companies cotton on to this and market to "travellers", but I liked it when locals just called us all "tourists" because that's really what we are. Yes, it's another form of consumerism.
I spent a year backpacking and it was mostly seeing cool places. I don't think it really changed me, but then I have worked and studied abroad before (there I go, pointing out how I'm not like the others!!). Considering those experiences too, I think there are two main things you're missing:
1) People who genuinely find hostel slogans like "live at the edge of your existence" deeply inspirational are probably late teens/early 20s and so for them it's all wrapped up in being independent, moving out of their childhood home, experimenting etc. Possibly the first time they've been out of their home culture and so even standard, Western backpacker hostels is a big jump.
2) A lot of people really find scary and challenging things you might be more comfortable with. Lots of people live within a few miles of where they grew up. If they go abroad, it's a package holiday on a resort full of people from their home country. Maybe a city break to be adventurous. Even though backpacking in SE Asia etc is heavily commodified, it's still a pretty small fraction of people who would even consider it.