C was unprincipled and pragmatic too, it was created with the goal of making UNIX portable. Still, C became one of the most popular and influential languages.
While I prefer ADTs/generics too, let's not forget that many people are less principled and pragmatic factors influence language choice as much (toolchain, ecosystem, popularity, familiarity).
The success of UNIX is inseparable from C and vice versa. C made UNIX one of the first portable operating systems and, by virtue of being low-level, provided performance.
There are good reasons that these startups weren't using OSes using Algol and Mesa. You seem to imply that the success of C and Unix is some historical accident as a result of two startups picking Unix randomly, and their choice was bit a function of the technical properties of UNIX and C. Which, is of course, nonsense.
Sun used Unix because Sun was co-founded by Bill Joy. By that time, Joy was already deeply involved in Unix (per BSD). If he didn't find Unix and C likeable and up to the task, they would have made different choices.
SGI and Sun were just one of many catalyzers, like a lot of programming languages have catalyzers.
Having had exposure to both C and Pascal at around the sane time, I vastly preferred working in C.
I do think there's something intrinsically good about it compared to other contemporary systems languages - I don't think it's just that it tagged along with Unix.
C was unprincipled and pragmatic too, it was created with the goal of making UNIX portable. Still, C became one of the most popular and influential languages.
While I prefer ADTs/generics too, let's not forget that many people are less principled and pragmatic factors influence language choice as much (toolchain, ecosystem, popularity, familiarity).