What are the arguments for and against Open Access?
While there's a great deal of complexity in the arguments, the primary arguments basically boil down to a very simple core of inclusion vs. cost.

For open access: Science should be available to all people, including the large number of people who don't have the personal or institutional resources to pay lots of money to buy access to articles.

Against open access: editing and publishing quality materials requires significant resources, and these have to be paid for somehow. If readers don't pay, then somebody else has to (often, but not always the authors or article), and it's not clear if these alternatives will end up making a bigger barrier for low-resource scientists. Moreover, a stable business model hasn't yet been established, and in the meantime lots of scammers have been attracted, who are putting out piles of trash and giving open access a bad name.

There's a lot more here, as noted in the comments, but this is a pretty concise starting point for understanding the arguments for and against.