Great insight on the environmental impact of tourism my dear!
Though you only brought up Bali in here, the issue is really at
a global level. No matter where in the world, tourism provides
a positive hike on economy but greatly undermines ecology.
We are sacrificing things like biological diversity, depleting the
ozone layer, and even climate change due to greenhouse effect.
In a much more localize level, I have seen its damaging effect
against the preservation of cultural values and heritage.

Unfortunately people need to survive in a very unforgiving, unstable economy and to do that Mother Nature is being sacrificed.
Third world countries are much more susceptible to fail because of
the lack of or inability to create and implement a good system. What you saw about Bali you'll see it in all of the big Asian tourist destinations apart from Singapore.

Regrettably I would say 90% of travelers only see the good bits and never the footprints they leave behind :-(