Dog poo is a "really bad and dangerous thing", at least according to my mum; she reckons that you can go blind if you get it in your eyes.
But that's exactly the reason why you should pick it up, as you wouldn't want some idiot kid getting it on his hands when rolling around in the grass then rubbing his eyes. A dog comes with responsibilities, and if you can't hack that then you shouldn't be walking the dog... and if there's no-one else to walk the dog, then you probably shouldn't have a dog (as it'd be unfair for the dog for it to be indoors 24/7).