Why is one length of patent good for all drugs. Create the cure for cancer I can see you getting 30 years, add a antacid to an existing drug you should get 5.
All the money going towards marketing would instead go towards lobbying, towards getting the government agency in charge of deciding "what really counts" for deciding that this drug should be one of them. When the US government was looking at how to create incentives for invention, they did look at rewards systems, and this was the common problem. Using the market system, for all its faults and ways it could be improved, at least sends proper price signals to producers and consumers.
The largest 10 pharmaceutical companies spent a combined $32.5B more on sales and marketing than R & D. No problem here? People are skipping dosing to stretch their meds further. Some people can't afford meds at all.