I'm all for space flight. A moon colony means less people on the Earth to pollute it. Same with a Martian colony, except you can cram more people on Mars and Phobos and Deimos than on the Moon.
*snip*
Having more places to live isn't going to mean less crowding at home. At the very best, it would mean your kids can now be forced to move to another planet in order to not have to struggle for survival. The problem is, the exact same thing that happens here on earth is no less likely to happen on the moon (which is, by the way, much smaller and has a significantly lesser biomass

).
"Put them on the moon" might work as an answer to "where can we put people when there's no room left on earth?", but that's a stupid question. If there are no
additional people, you don't have to worry about where to put them.
Of course that falls apart if one group of people (a country, a religion, people with the same ethnic background) works on population control and another doesn't, because then they have more people, thus more workforce, more potential military manpower, more potential democratic voters, ...
Then again, the Human species isn't known for it's smart decisions.
Thing is we don't make decisions as a species, we make them as individuals. And any "good for future generations" planning or decision-making depends on our personal views of what is good for them. Things like:
- Is being very numerous but with a poor quality of life preferable to being few but content?
- Is one person being euphoric better than several people being content?
Welcome to the hard parts of moral and ethical philosophy.