Autocompleting strings is something that allows you to take a shortcut (if it guesses correctly) but is completely ignorable if you never use it. Like, seriously, if you never looked at the bar while you are typing, it behaves the exact same way as if it had never been implemented.

Meanwhile, the omnibar changes old UX behavior to allow Google to MITM requests if people don't recognize it and update how they work. And most people didn't.