We've been waiting for 6 years, there are tons of chinese (massive ping) servers cluttering the serverbrowser when searching for a well-populated server. Please please please finally add this feature...
Hmm, I think that because the servers are independently hosted, that they would need too add something on the server config side, that displays what region the server is in, and because there are not a lot of servers that are populated, this would further limit exposure, and I don't think you would get the server community onboard.
What I usually do is click the "ping" button on the top right, and sort by latency to find a good server, however a lot of servers are available with a pretty decent ping because i'm on the east coast, so this may not be as viable depending on where you are unfortunately.
I agree with soraflair, it would be hard to implement it.
What I do is favorite the servers in my region so it is easier to spot them in the server list. That way it is easier to scroll through the list and find the servers you are looking for.
I sort servers by ping and favourite the servers I play on most often. Works well so far.
Can note it, but as @soraflair has mentioned it could impact a lot of servers in a negative way.