LibCURL is used (along with a TON of other 3rd party C libs) in a bunch of systems securely. Writing C code isn't __always__ insecure. It all depends on the developer/team. Just like writing Java isn't always portable.
It seems like it's all about saving dev time these days. I was once pulled onto a project where some devs had used perl & python for an embedded system. They got a prototype system up pretty quickly, but performance just wasn't there and they were using WAY too much RAM/CPU based on what the system had to offer. They wasted many man-months trying to optimize their code. Eventually, they brought in some C devs and we rewrote in C and the system ran great. It turned out great for the Python/Perl devs too because they got to learn C and some of the benefits of using it.
Don't get me wrong. C doesn't fit all problems.