A couple of specific things that jumped out at me, as someone who lived through this (and got hooked for varying amounts of time on several roguelikes and roguelites):
I strongly disagree that today's world has the best of open source & proprietary. (Also, omitting any mention of Free software is a little odd.) We do have a mix, but it's neither the best nor the worst to be had. The proprietary mindset has infected the "programmers with free time" community, to the extent that one reason why you don't see ambitious user-facing projects is because the profit motive has drained away enough energy and talent that the engine of open source development just kind of sputters along until things start to risk taking off, at which point someone will come up with an idea for monetization. And monetization kills the "true" open source spirit dead.
On a related note, pointing fingers at open source games for lackluster design and poor user centric thinking is a little ironic, given that the exact same thing ails today's commercial game scene. Loot boxes and more subtle forms of the same thing have largely destroyed the freedom and original thinking that used to create interestingly novel experiences. We had a period where the indie scene carried that torch, but it has now been subverted in much the same way as the open source scene.
There are plenty of individuals or small groups out there who still have the fire, but it seems like getting any traction (whether by growing a community or gaining users/players) brings those people in too close of contact with the poisonous influence of profit or fame or whatever, and it takes a strong character and quite a bit of privilege to resist those influences. Temptation is everywhere.