I have some sympathy, but not a lot, because I don't feel like this is a problem with the web. Honestly, just based on what I used Flash for, the big thing I miss has nothing to do with Actionscript or any of its code or distribution. Distributing SWF files was no easier than it is today to distribute an HTML directory in a zip file, in either case the only reliable way to share your stuff was to link it on a website…
This is a really good point. It PAINS me that when somebody wants to upload a friggin' cartoon on the internet they have to render it out to 100X the native size and introduce compression artifacts. We were more sophisticated than this in 1999!
There isn't one. Why? Flash clearly showed that people like to make animations with vector art. It compresses well, you can do nice things with scaling. And independent of everything else, there just isn't a clear best tool for that today.
I honestly feel like some of this comes down to, somebody needs to look at Flash and say, "hey, having nested timelines inside of symbols that can be edited on the fly is a really good idea, and maybe some program somewhere should do that." I don't understand why that hasn't happened anywhere.