Once upon a time, the medical opinion about ulcers was that they were caused by stress, it was not until 1994 that the NIH published the opinion that most ulcers were caused by Helicobacter pylori, and in 2005 the Nobel Prize in medicine was awarded to Marshall and Warren. About the first time I heard about antibiotics curing ulcers was by a radio call-in doctor (an actual MD) in the mid-80's- he also preached about a cure for asthma involving long term antibiotics. It may be only applicable to specific types of asthma- but there has been very little research into this cure (admittedly, there are real risks to long term antibiotic usage)- which involves not a new medicine, but the administration of an existing medicine.
Unfortunately, it is an economic decision by the drug maker- continue with an existing, proven (multi billion dollar/year) revenue stream, or risk that revenue stream by developing a treatment with a very small revenue potential (I believe your estimates for the cost are *way* higher than the market would bear).
The unfortunate part is that health care is not about health first, it is about money first.