Users are free to block the execution of client-side scripts though we all know what that means: much poorer to non-functional UX in many cases. Plus, to an extent browsers can control what can be collected on the client side, e.g. location, microphone input etc. (I wish there were similar restrictions on the keyboard and mouse, maybe some day we'll see that too)

But I'd agree that letting the users use a public resource on a condition that they should allow arbitrary scripts to be executed on their side can be considered unethical.