What Adobe got right with Flash (and Blender unfortunately failed to do for 3D) was entire self-contained production pipeline within a single product. You get to fire up Flash IDE, draw in it, layout in it, add scripts to it, debug there, test, publish, and voila - game done. This led to huge productivity/creativity boosts and single-man chop shops.
I had my little hybrid Tablet PC back in 2008 where I'd fire up Adobe Flash IDE, get to draw on it with a pen with pressure sensitivity and custom brushes, swivel to PC mode, get to some coding, attach scripts, debug some, and get my game prototype up in few hours with decent hand-drawn art. Hell, I remember fully completing (to production binary, with zero or very little tweaks afterwards) some adver-games in under 3 hours.
Imagine that - you need just a single application to do absolutely _everything_ in order to publish a successful game. Fast.
I'm still waiting for anything even remotely close to that in terms of both quality and features, on _any_ other technological platform for game development, lest one that was immediately deployable to >99% of potential customers.
You have a very good point there, though to be fair Macromedia got that right and then Adobe proceeded to screw it up. Adobe never liked the idea of using a single application, they like to sell people a range.
There's a lot of "dead" languages that have specialized use and continue to feed people. However, the world where Flash was supposed to be an ubiquitous business platform is much different than developing games.
Flash is not going anywhere any time soon.