Flash was great and I haven't found a direct replacement yet (GameMaker Studio 2 is the closest I have found). I pumped out 8 Flash games about a decade ago that generated enough ad revenue to cover all my bills for a few years! I miss how easy it was. Another huge win is how effortless it was to distribute Flash games (they spread like wildfire after I uploaded it to one or two sites).
It's not the loss of Flash per se (as there are plenty of rapid game making tools targetting HTML5 about) it's the complete collapse of the supporting infrastructure.
Mochi Media closing was huge. I went from getting a steady trickle of money for games I wrote to nothing.
As far as I can see there is no Mochi for HTML5 games. Every portal is its own closed environment.
A friend just messaged me telling me that i need to check out Scirra Construct; apparently that gives a very Flash-style interface to build games. I'll have to play with that.
Unfortunately most of Roblox games are just attempts to siphon your money by buying Robux. Their target market, kids around 8, beg their parents for Robux so they can buy some stuff in one person's game.
It's incredible how much money they make through tactics that make many of their games not really enjoyable unless you spend a lot of money in them.