Flash causes more crashes than any other application for me on both OSX (Safari) and Windows (Firefox).  It's horrendous.  Flashblock / ClickToFlash did the same for me, I nearly don't crash anything any more, and I don't fear losing all my tabs by opening a random website.<p>As to the "flash where flash is useful", hopefully JavaScript + the canvas will eliminate the majority of those cases.  There are still some cases where flash is significantly better, but they're pretty rare.  Most of the time I highly suspect it's popular because of the nice editing tools, not because the producer(s) wanted to target Flash.