Agree! They could have cached way more of this. A pre-rendered video would have had the same effect. A fun and impressive thing to build for sure, but its value isn't worth its complexity.
I wonder if I'm just odd, or if people not realizing it's interactive is widespread.
Of course part of the art is that it is real time (ish). That may be harder to do with video. (But I guess it could be a live stream)