It might seem trivial to compare the inconvenience of a doctor's appointment to the tragedy of meth addiction. But a law that requires a prescription for pseudoephedrine is going to have health consequences for innocent Hoosiers while doing very little or nothing to stop people from using meth.
Even with health insurance, very few people are actually going to go to a doctor to get cold meds. First of all, all Hoosiers live within 70 miles of the state line. So going to another state will be less of a hassle than going to a doctor. Some Hoosiers might stock up on cold meds as well. And some people will choose the worst possible option: going to work or school without controlling the symptoms and placing coworkers and classmates at risk of catching a cold.
If your sole objective is to stop meth, it would make for sense to lobby the federal government to reclassify pseudoephedrine as a Schedule II drug like Adderal or oxycotin. A state law in this case is a pathetic half-measure. On the other, if not even Congress can be persuaded to outlaw a drug, then that should be an indicator of how silly the whole idea is.