Having BASIC (or another language) built into the machine was a big plus and encouraged people to see continuity between the OS, the hardware and the code.
If that BASIC had to use built-in functions and data-types instead of simply POKE-ing and PEEKING-ing as a de facto interface with the underlying machine code, that would still have been hacker-friendly without being inflexible.
It was such a weird relationship between desktop machines and UNIXes back then. It's like the desktop designers had to re-learn the lessons of UNIX in the small. So much was forgotten.