For public places, people's lawns, and spots that have a lot of foot traffic, definitely.
I live in a rural area so people picking up after their dogs is pretty rare, actually, and personally don't see any reason to do it out here. You run across places where other dogs have relieved themselves around here all the time and no one makes a fuss over it. There just isn't enough foot traffic. *shrug* People looking in from the outside think it's disgusting to leave it (where it honestly isn't going to bother anybody), but I think it's more disgusting to carry my dog's waste back home with me. I definitely understand the reasoning for it in more populated areas and would swallow my disgust for the process and do it if I lived somewhere different.
If my Tazer has to go when I'm walking him, I always make sure it's not on someone's lawn. It's usually in the brush along the side of the road or something. He's gone IN the road on a couple occasions and I've had to find a big leaf to move it to the bushes. (yuck!) If I take him to the park, I clean up after him. And if he goes on part of our lawn that's close to the house, then I also clean it up so we don't step in it (our lawn is like 4 or 5 acres [yes, that's mowed lawn]).