The ability of a non-scientist to understand a paper at a useful level varies greatly based on the area of study and the reader's knowledge of the topic. 'Basic scientific literacy' may not be enough, but there are many more individuals with an amateur level of advanced understanding or interest in a given area who benefit greatly. I personally have no institutional access but I read a lot of papers that I can understand with an undergrad level of science background and a keen interest in a specific subject. I'm sure there are many others like this.