Yeah, no reason to redirect every 404 to the root. There's nothing wrong with 404's, but if you're trying to be tidy and improve user experience, you can do one of two things:
1. Redirect the 404's to relevant pages/posts (don't send them all to the root, though)
2. Create a custom 404 page that has links leading to your other pages with a message like: While this page doesn't exist anymore, check out one of our other pages here: