You're missing the point. We live in an environment that reinforces obesity, see also car-centric lifestyle which is an infrastructure problem. It's not like humans "wanted" to be active before, it's just that their activity was easily covered by work and travel without needing extra time and effort PLUS they may have already been at/near a caloric deficit just eating what was available to them.

Also I am not fully weened off sugar, but honestly I find a lot of things unpalatable due to the sugar content (like milk chocolate). I would be perfectly fine if sweet on its own wasn't a primary flavor anymore. That and it's at the point where you need to assume that there's a significant amount of sugar in basically everything. For example, Ireland classifies Subway's bread as cake due to the sugar content.

Sugar is cheap (and can be put in higher concentrations than in the past), and it makes sense to make unhealthy food cheap. I also wouldn't look at the opioid epidemic or similar problems and say "only personal problems here".