Battery life wasn't really a thing I worried about before smartphones came along, so I'm not sure that's super relevant (although, if you want to pick that fight, Unity on mobile is a real battery killer). Security was rough, but I think I'd trade a bit of security to ditch the walled gardens we have today.
I do think things are better in most ways for users. Because Flash portals didn't require a download, it was MUCH easier to try new things. This led to a virtuous cycle of people making weird shit. Because so much game content is gated behind app stores these days, you have to download a thing and then wade through permission/notification screens and it's too much of a cognitive burden compared to "oh, that looks neat." (Toss on that app stores are horrible for discovery). I think the way most people discover (mobile) games these days is through ads, and if a game is running ads they're a large company with plans to extract $5-$10+ out of you...
So we've traded big catalogues of free games with crappy banner ads for walled gardens that depend on ads for discovery of exploitative IAP skinner boxes.
I miss flash games and scene that existed around it. Including free aspect of it and ease of development of it. I do not care about complex games game studios put out.
So from a user's standpoint, things have become better not worse – they don't have to compromise security or accept horrible battery life in doing so.
From the developer's standpoint, things have improved too – they don't have to depend on niche toolchains and they have better monetization options today than ever before. For small game studios it is easier to find mainstream developers who can do game development rather than only those willing to master niche toolchains.
The side-effect of using mainstream toolchains is it has more moving parts and hence has more complexity (that is unnecessary at a solo developer scale).
I agree that the learning curve has become harder a creative arts designer who wants to be a solo game developer to express their creativity.
So maybe the real question is what are the accessible mediums in which creative digital artists put out their hobby/amateur work today?