Exerciseforlife, I agree with some of the points that you made. Especially that fewer people are working physically demanding jobs, the cost of healthy food has gone up, and that many activities (snowboarding, boating, etc.) are expensive.
A lot of it still boils down to the fact that people want to lose weight without putting any effort in.
If you are gaining weight because you sit at a desk all day long, then you need to be active outside of your workplace, find ways to get up off of your butt during the workday, or get a new job where you are on your feet more often.
Generally, people who are overweight eat too much. Yes, healthier food items might be more expensive (although I tend to disagree with this, as a bagful of produce is much cheaper than a bagful of processed foods...). However, people who buy processed food and are overweight tend to eat more than they are supposed to anyways, so they are likely overspending on food because what they are lacking in quality, they are making up for (and more) in quantity. I would rather spend more on higher quality food, but eat the appropriate portions. So yes, you might have less food in your fridge after a shopping trip, but you will be less likely to over-consume.
As for the activities being expensive... yes, I can see that that can be quite discouraging, but people are more than willing to spend money on eating out, alcohol, movies and other activities that are not great for one's health. So, it's often more a matter of priority and proper budgeting.