Right-click is very useful in some cases. I have some productivity apps I have built for myself using web technologies, and it's extremely useful to be able to have custom context menus. Since web applications are doing more of the work that native apps used to, I'm ok with some level of annexation of the browser's UX territory when a site can really justify it.

That said, I would be in favor of an option to disable it globally, or for certain domains.