That's like saving good riddance to the internal combustion engine because we would be healthier without it, as if we've had better alternatives all along. If it weren't for Flash, we might all be complaining about Java applets right now.
We've had better alternatives on the desktop for over six years now, since Apple said "No Flash for iOS" in April 2010, when content creators panicked to capture that market and started conversion to HTML5 video. That already was a long time coming.
Chrome finally saying farewell to Flash in this manner forces the market to recognize that Flash is no longer an option even on the desktop.
As for my security argument: using the link above, if we start with vulnerabilities found in Flash Player after April 2010, that's still 830 of them.
Beyond that, one of the most significant areas of flash as a player is eLearning, training and simulations. Say what you will about a lot of the garbage in player, the authoring tools were some of the best available... though I haven't seen what Adobe has on deck today, it was a very nice experience with nothing comparable for at least until 2012 (last time I worked with flash/flex).
What my real hopes were when adobe bought Macromedia, was that they'd open up the format, and convert it to a packaged zip file with a manifest, svg and javascript proper as the language. Allowing for browsers to co-opt and internalize the players. Then adobe could continue to make great tooling and the browser vendors could correct the ship on the players. My dream is pretty close to what Silverlight offered, but that was something nobody was willing to look at for good enough reasons.
I emphatically agree. Back in 2004-2006 I was doing Macromedia Flash MX 2004 development (with the new-and-shiny ActionScript 2.0! Based on the forthcoming ECMAScript 4 standard that should be finalized any day now...). It was hands-down one of the best development environments I've used w.r.t. creating games and "rich Web applications". It really was the best thing available at the time: you could draw and animate your sprites, tiles, backgrounds, whatever within the same IDE in which you wrote your code. You could attach scripts to any object on- or off-stage, and they ran in an event loop. The documentation it shipped with was also excellent, and I picked up a hardcopy of the "ActionScript 2.0 Bible", a massive tome of beginner's tutorials, intermediate tips and tricks, and complete language and library reference -- for a measly $20.
Nowadays, Unity gives a similar yet more featureful environment for writing games, and Silverlight briefly presented an alternative for "rich content". As far as rich content goes: sure, we can do that stuff with HTML5 and JavaScript nowadays, but it was just so much more pleasurable to work with the Flash IDE than anything else I've seen, excepting maybe Silverlight. Where making a Web 2.0 application feels like an enormous pain in the ass, making the same in Flash was a joy. It was fun rather than frustrating!
I think if Adobe (or even Macromedia) had opened up the Flash format (SWF), and maybe even the plugins, things would've gone a lot differently. Flash could've been a law-abiding citizen of the "Open Web", and we could've seen some healthy competition amongst development and runtime environments. The community at large could've found ways to iterate and improve on the technology. But, I suppose that ship has sailed and we're stuck trying to jackhammer the round peg that is application delivery into the trapezoidal hole that is document delivery (i.e., the Web).
For video, HTML5 video was simplistic before DASH, which became a standard in 2012. Further, with Flash your choice of codecs was easy (Sorensen Spark, and later H.264); with HTML5, you have to stream in whichever combination of audio and video codec and container the browser supports.
For rich interactivity other than video, we're just now, in 2016, at a point where we can claim the Web Platform [1] finally is on par with Flash, but sites like CanIUse still exist [2], because not every browser supports every new API. Flash gets a (rightfully) bad rep for its security vulnerabilities, but it was a single platform to target, and it's been replaced with alternatives that are no less subject to vendor pressures, despite being 'open' and 'neutral'.
Vulnerabilities aside, at least Flash runtime didn't give unfettered access, and was even nice enough to ask for permissions to the webcam and microphone. Furthermore the runtime was frequently updated and patched by the vendor, and Flash being embeddable in web pages made keeping up-to-date individual Flash applications easy, as they were hosted on the server.
I'm not sure I'd call that "better". Running, albeit a bit worse, is better than not running at all.
it did, see Adobe AIR, publishing to Windows / mac OS X / iOS / Android is imho cross-platform enough.
In the case of about 95% of the Flash that's been written, we have had a better alternative all along: Not writing Flash. Not animating the self-help menus at your ISP, not auto-playing music at every restaurant website, not cramming a megabyte of crap into the ads coming down your 56kbps modem connection, etc.