Interestingly, Google Chrome recently moved in the opposite direction, and removed support for having Flash off by default and activating with a single click. Instead, they consider Flash to be "important plug-in content". While they allow you to have it off by default, rather than "click to play", they now require that you right click then pull down to "run this plugin" each time you want to activate: https://productforums.google.com/forum/#!topic/chrome/xPcpRB...
I presume this is because they want to discourage people from having Flash off by default, since this would mean they would miss too many Flash ads. I took this as an opportunity to try out some different browsers, and found that Opera met my needs slightly better than Firefox. If you are looking for an alternative to Firefox or Chrome, or just want to see what's out there, you might want to check it out too: http://www.opera.com/
ps. As an example of the new Google interface strategy, to show all the responses on the Google Chrome Help Forum link above rather than being forced to click on each one, you can press the 'o' key some random number of times until they appear: https://productforums.google.com/forum/#!topic/gec-answers-f...