It takes more time for us to have plugin-free web, plugins are never safe and secure-especially from Java are often suggested by security researchers to disable or remove. Mozilla already made plugins in Firefox to click to play except for Flash,  but browser by default enables them including installed by third-party applications after installation such as Adobe Reader or Foxit Reader on your computer, which brings unwanted security risks to the browser and also degrades browser performance.

Firefox new plugin deactivated

Automatically disable new Plugins in Firefox

Meet New Plugin Disabler extension which automatically disables new plugins installed in Firefox and extension shows notification on top right corner of screen about when it does this thing.