About fifteen years ago I was starting to struggle with sciatic nerve pain due to years spent driving a car with a heavy racing clutch in traffic, and a lack of exercise.
Wow, nice to hear someone in a similar situation. I also have sciatic pain (thankly no slipped discs or serious stuff like that) due to too much sitting on my ass. However it's now getting better thanks to increased exercise.
I surely have walked and bicycled aplenty, but my abs and back muscles are garbage.
Web pages have always been a bit unreliable technology. Who doesn't occasionally meet a page that is almost loaded, but hangs there waiting for one element to be downloaded? At I meet a few times a week a page that gets "stuck". Then you refresh the page and it's fine. Why does this problem still exist? Can't the browser at least quickly try reloading that element?
Imagine if desktop GUI apps were like that. That some GUI element would just randomly not show up. That would be unacceptable.
Why is it released for "non commercial use", why does it matter to Pixar if it gets used in "perrsonal projects that do not generate commercial profits"? Does it stop RenderMan working for Pixar if a human or a commercial entity makes money from using it?
It requires a big team of senior engineers in mathematics and computer science to create and support something like RenderMan, so it's not unreasonable that they ask money for it.
The idea is probably that hobbyists (many of whom wouldn't have enough spare money to buy it anyway) can get familiar with the software, and then Pixar can sell the software to commercial use where the actual bucks are made. For a fully commercial tool I see this being a pretty nice deal.
Even then the real license costs just $495 per seat, which is cheap. You can easily recoup that investment.
The hardest part of climbing the ladder of success is getting through the crowd at the bottom.