you will get better answers to your question, and a more productive discussion in general, if you leave your subjective opinion out of the question.

it’s not fully memory safe (there are some programming languages that are even safer, like Ada)?

for example, you might ask instead “why has Rust gotten widespread adoption, that previous safety-focused languages like Ada did not enjoy?”

this is a big ol’ “it depends”

if it’s a hobby project, then by all means rewrite it if you want to.

if it’s a commercial project of some kind - there’s a business that’s making money, and part of the business making money relies on this code working properly - then rewrites are almost always a bad idea.

read Things You Should Never Do, Part I, an almost 25-year-old blog post (man, that’s a weird sentence to write) about why giant rewrites in a commercial setting are a bad idea.

in general, people greatly underestimate how much work is involved in a rewrite. it feels like it should be simpler to start from a blank slate, and tell yourself you’re going to avoid all the mistakes that you hate with the existing codebase. maybe you’re writing it in a new language, or at least a newer dialect/version of the same language.

if the current codebase is a mess…how did it get that way? lack of engineering discipline? a “just make it work now, we can go back and tidy it up later” attitude towards accumulation of tech debt? if those same attitudes are present on the team doing the rewrite, you’re going to end up right back where you started after the rewrite is “done”.

the main things you need for refactoring to be successful is a) tests, and b) a plan.

the tests allow you to refactor with the confidence that if you break something, the tests will point it out for you. trying to refactor something that lacks tests is the worst place to be in, because you’ll want to add tests, and often adding tests requires refactoring the code to be more testable, placing you in a catch-22.

the plan allows you to make those refactoring changes gradually, over time, while still maintaining the system. in the context of a business that’s paying developers to do this work, the businesspeople tend to look poorly on an engineer coming to them and saying “we’re gonna spend the next year or two doing a big rewrite, so in the meantime you can’t ask us for any new features or bugfixes to the existing system. but once it’s done the new system will be really cool, trust me.”

successful refactoring is a Ship of Thesus - you can replace the entire thing, but you have to do it one component at a time.

you read a post about how awesome C is, asking why more people don’t use it and instead gravitate towards replacements.

you ctrl-F for “security” - no mention

“buffer overflow” - nope

“memory safety” - nothing

“undefined behavior” - nada

this is sort of a reverse Chesterton’s Fence situation. the fence is getting replaced, and you’re talking about how great the old fence was, without understanding any of the actual problems it had.

you wrote some C and found it simple? OK, great, congratulations.

go work on a C codebase that spans 100 or more engineers all contributing to it.

go write some C code that listens on a TCP socket and has to deserialize potentially-malicious data received from the public internet.

go write some C code that will be used on an aircraft and has to comply with DO-178C.

and so on. after you’ve done that, come back here and tell us if you still think it’s “simple and effective” and “applicable everywhere”.

there is a reason C has stood the test of time over many decades. but there is also a reason it is being replaced with more modern languages.