I also hate flash, but my view is that in combination with IE, it kept the web back 10 years.
When I first started out as a dev, barely anyone knew HTML or CSS, because flash was all you needed. It's seems bizarre now but I took a lot of ridicule from people when I tried to insist on building things the standard compliant way back in 2004. I remember being told that things I had personally designed specifically to be built in HTML couldn't be done. The situation was bananas, flash had turned everyone into zombies. And while you wouldn't be fired for mentioning JavaScript, you would jump to the top of the naughty list. Advocating JavaScript back then was like advocating kiddie fiddling.
And so web standards were kept back. So browsers were held back. (Why should Microsoft make a better browser? Nobody uses HTML or CSS anyway?) and so the whole web was held back. I look at a lot of the stuff we do today, and I see no reason we couldn't have been doing it back in 2004 other than the fact that flash was easy. It's was the crack that turned the web into a digital ghetto with developers high on their own success, site owners tripping off the rich, colourful and "fully immersive experiences" (there's a phrase you don't hear anymore) of their own all singing, all dancing and utterly unusable websites. Meanwhile, users were left to scrounge around in all that dirt looking for scraps of anything barely edible.
If IE was Hitler, Flash would be Stalin. Sure Hitler was a bad guy and he shoulders all the blame, but he was rank a rank amateur compared to our friend and ally Joseph "evil personified" Stalin.
On top of all that, the flash player is a piece of junk. Always has been, always will be and I make no apologies for feeling smug when they started scrambling to get it working on mobile. "Oh no!" I would say, "have all those years of showing nothing but contempt for the people who have to run you're buggy, resource hungry piece of shit plugin left you up shit creek without a paddle?" Good riddance I say.