It's always dangerous to say "I've used this X years / written Y lines of code and never needed Z". No-one has experienced every use case.
Related Posts
I've heard of 'blub languages', where you don't realise that other languages have better abstractions until you've experienced them.
I think the same thing happens with individual features. I've seen several C++ folks miss variadic generics in Rust, but I've not written enough C++ to feel it.
I travelled recently with six electronic devices, and every single one used USB-C for charging. It was wonderful, and not an experience I've had before.
It's really satisfying to use a profiler for the first time on a project. I always find a big performance win with only a small code change.
It's never the code that I expected to be slow, however!