Megan McArle explains simply why cutting the profits of drug companies will damage R&D. A quote:
I don't think of R&D as a budgeting problem; I think of it as an investment problem. After all, even if the pharmaceutical industry has no profits right now, they can borrow the money in the financial markets at fairly attractive rates.
The main obstacle to R&D, then, is not the current state of pharmaceutical industry profits; it is the potential return on the investment in R&D. After all, Merck doesn't have to make drugs; it could generate a nice, safe return of 5% a year in government bonds. Or it could get into some other business, such as making soap. If you drive down the profits on new drugs too far, it stops making sense to invest in new drugs, even if there is a small profit to be made on current production.
Exactly right. In fact, I feel that it was wrong to institute time limits on drug patents. (h/t, Big Pharma vs. Big Gov at NE Repub.)