> Patents are essential to the current business model of pharmaceutical companies -- they are necessary to guarantee a return on investment, but the portion of the investment devoted to R&D and clinical trials is dwarfed by the marketing.
Your comment contradicts itself.
If, as you say, patents are "necessary to guarantee a return on investment", then it doesn't matter if the R&D is the largest cost or not, because the company won't produce a profit (and therefore won't produce new drugs) without the patent.
In fact, it's quite reasonable to think that both massive marketing and time-limited protection from competition are necessary to ensure enough of a return to guarantee continued investment into the industry. It doesn't have to be one or the other.