It's not poo bags that piss me off, it's this: people who take their dog to the park and pick up the poo like a responsible owner... then walk a metre down the track and chuck the poo bag on the ground.
If you go to the trouble of picking up your dog's poo, make the effort to walk to a bin and dispose of it properly.
Don't just make a token effort because people are watching then get out of sight and ditch the poo package..
Dropping your poo bag is worse than not using one in the first place. I'm pretty sure that a plastic bag full of poo is much worse than a natural, organic poo left to decompose.