The trick with body weight exercise progression is to use leverage to increase the effective resistance. For example: http://stevenlow.org/the-fundamentals-of-bodyweight-strength...

Done correctly body weight alone can allow one to achieve great strength. In fact, it’s probably superior on account of gymnasts can easily do weight lifting exercises while weight training doesn’t really transfer to gymnastics.

If you keep some progression going, and don't over-eat, you'll end up with a pretty nice physique at least.

I think a big reason why so many have a hard time maintaining a life-long fitness habit is because their goals are merely cosmetic. The first thing an excercise routine needs to be is fun, and after that the rest is butter.

The entire discipline of calisthenics would disagree with you on this one... (oh, and me too)

The discipline of calisthenics does not consider plain push-ups, bodyweight squats and crunches as anything more than beginner-level exercises.