This is the worst kind of busy-work. Rewriting something for the sake of it is terrible practice.

There's a lot of refreshing energy amongst Rust coders eager to produce better, more modern command-line tools. That's amazing, and a real benefit to everyone. But rewriting simple, decades-old, perfectly functional tools, with the explicit goal of not improving them is just a self-absorbed hobby. And a dangerous one at that - any new code will contain bugs, and the best way to avoid that is not to write code if you don't have to.