But BASIC on those computers was interpreted, and thus far too slow. Even the C compilers weren't that great. Every real game, AFAIK, was written in 6502 assembly.

True, yet it made lots of kids happy to try out programming their own games and now they work across the industry, including myself.

Not everything is about the ultimate performance.

The point is that it's not "javascript interpreted in machine code", which in my opinion would make these computers far more fun, otherwise they're just fancy game frameworks.