Flash is to web dev as Excel is to desktop applications: it "sucks" but is also arguably the single best tool the entire field has produced. The technologies that might replace Flash are "better" but also so much worse that they aren't even close to actually replacing it, years on—and, yeah, that's mostly about the authoring tools, which were not just excellent, but also de facto free for hobbyists (thanks, piracy) when Flash was in its prime.
not only that, the shovelware scene proved that it was piss easy to use, and powerful (especially in the later years)
see as many html5 gaming webpages lately? yeah, no. the 'death' of flash killed the browser game and rapid prototyping that flash offered, and there is nothing on that level in this age.
the problems that html5, css and javascript could in theory 'solve' are a moot point when the switch to those technologies killed any enthusiasm for it.
