A thinner version of the PET bottle is available. As soon as it becomes strong enough for the carbonated soft drinks look for those to be in thinner bottles as well. The reason they are not used now in soda is due to the carbonation and the nitrogen used in production make it too weak to withstand the handling shipping and "other" shakes along the way; it creates too much pressure and could result in failure.
For those old enough to remember it will be somewhat like going from the "hard" metal soda cans to the new light weight aluminum.
Whether you think can or think you can\'t, you\'re probably right!