tldr; walking for any health/fitness/aesthetic reasons isn't a logical choice.
No amount of walking will undo bad dietary choices, such as those that led to overweight/obesity in the first place. Frankly, if walking is a genuinely entertaining activity then one should do it -- but one ought to be informed that there won't be any tangible results after the first few weeks. Compare walking calories/hour (100ish?) to sitting calories/hour (75ish?) -- maybe 25 percent more? I could walk three hours at a vigorous pace and accidentally eat all those calories back by mismeasuring my cooking oil for one meal.
The reason people are critical of such a low-key endeavor is because they're comparing it to the absolutely drastic changes one can do with weight training,even if you really don't want to try too hard. I'd expect to take a totally untrained man into the gym and have him double his strength in a matter of weeks; and over three months he'd gain 5-10lbs of muscle, depending on how hard he pushed himself in the gym. Totally noticeable in terms of definitionand posture. Even lazily lifting 3 hours a week will pack muscle on (in the first year). Walking won't accomplish anything other than make someone think they're being productive.
Obviously, to each their own -- if dood says he'll never do it then that's his call to make. I think we're all just saying ("You sure about that, man? It isn't that bad and it's staggering how fast the benefits manifest themselves.") Plus, in my experience, most people saying they don't want to engage in something like weight training haven't ever done it, they're just opposed on principle. It isn't an informed choice.
