If C is simple and clear why is it fraught with pitfalls? While C code can be nice and clear to read that doesn’t mean there less mental burden on the developer to keep track of everything going on.
The argument against "Why dont they just fix X?" usualy commes down to: it would break millions of lines of code, make every C tutorial/book obsolete and force millions of C programmers to learn new things, not to mention that if we broke the ABI, we would break almost every other language since they depend on Cs stable ABI. Breaking C would literaly cost tens if not hundreds of billions of dollars for the industry.
Look at the move between Python 2 and 3. The cost of breaking bakwards compatibility have probably been astonomical, and then there is way less Pyton code being maintained then C code.
C operates on a scale that is almost unfathomable. A 1% perfomance degredation, in C will have ameasurable impact on the worlds energy use and co2 emissions, so the little things really matter.
C is "simple" in the same way DNA is "simple". There is a small set of very straightforward rules, but that set provides immense flexibility. But it in no way means that any resulting object will not be complicated. Perhaps a better word than "simple" would be "non-complex", making the distinction between "complex" vs "complicated" systems.
By contrast, the features you refer to would increase the "complexness" of the language (I won't even dare use the grammatically correct word "complexity" here, lest we deviate into yet another trap of conflating definitions).
Which, I would agree with OP is, for better or worse, probably far outside C's goals as a language.
You can get into pointer and memory errors in C++, Rust and Ada. All of them low-level system languages. Sure, those errors might be harder to produce, but not impossible, and definitely easy enough to still trip you up.
I programmed in all of those languages, except Rust (just don't like it). At least in C you pretty much now WHY (not necessarily where in the code) things went south, without consulting a thousand page specification or having to remember the myriad of language feature interactions that could have triggered those problems.
Moreover, C being small, it's a good on/off language. Try doing a code review for a C++/Rust/Ada code base which uses features heavily after not having touched the language for a year. I bet it is not as easy as C.
You know, some things in life are just hard. And low-level programming is one of those things. C is only honest about this.