Yes, it is a better practice to serve content directly from the domain root with a 200 OK status.
However, I have worked with sites who placed their home page in a directory - there were technical issues with their set-up that were challenging for them to work around. They used a 302 Temporary redirect for the domain root -- that means Google indexed the domain root as the url, but with the content of the redirected page. This worked for them, and they do fine on the SERPs, even for a search on example.com.
So, if you can serve the content directly from the domain root, definitely do that - it's the best. If not, then a 302 is second best, IMO.