First off, that's not sales and marketing expense. It's what accountants called "sales and general administration" which yes, marketing falls into, but so do a number of other items. It's not 100% marketing.
Second, the only reason why a company would spend money on promotion is if the return is >100%. So, if drug companies were to stop all promotion, their profit would actually fall, not go up. So it's not going to reduce the cost of drugs.
Third, I've talked to a number of physicians would appreciate the marketing that drug companies do. They don't have time to keep up on the latest, so a 15 minute chat with a drug rep might save them a lot of time. Of course, they know the marketing is biased, but it at least gives them a sense as to what's out there.
