Because who would pay for RnD if you can't go exclusive at least for a dozen or so years!
Well I hope that someone would, that the human social structure have evolved enough to create all what's necessary for it's survival and that the pharmaceuticals industry wouldn't collapse, it would just restructure and medicines will be cheaper!
The sad truth is, I really believe this would what would've happened!
"evolving human social structures" is just hand waving. What would the economics of your patent-less pharma world look like? Research dollars are a scarce resource - how will they be allocated and by who?
The sad truth is, I really believe this would what would've happened!