One argument is that getting a patent ensures exclusivity to use the technology. In turn, that drastically improves the likelihood of getting a return on any investment dollars. And finally, that attracts a lot more capital than a non-profit or gov't funded agency could typically get.
Like PCR, CRISPR is a relatively simple technology. It doesn't require billions of dollars of R&D to make it useful. Less useful gene editing tech (Zinc fingers, TALENS) have already been used in clinical trials. So just like PCR or that blood Myriad Genetics gene patent on BRCA1, patents hinder progress, make research more expensive, and impair new companies from getting started.
The problem is most tech-transfer departments that universities have actually lose money after paying the lawyers[1] is taken into account. Public research should belong to the people who paid for it -- the public.
One argument is that getting a patent ensures exclusivity to use the technology. In turn, that drastically improves the likelihood of getting a return on any investment dollars. And finally, that attracts a lot more capital than a non-profit or gov't funded agency could typically get.