MapleStory is a game where you usually have more than one character. This is why I believe an account based friend list would be greatly beneficial. Not only would this make communication and visibility better between friends, it would also make our friend lists more concise. The Elder Scrolls Online friend list is a good example: https://i.filehostingsite/Gn6gdYM/ddd.png (Source) https://i.filehostingsite/Y35m0pS/dddf.png (Source) In this game, if you hover over the account name, you will be able to see the character they are logged in with. We can also look to the friend list in League of Legends for other possible features: https://i.filehostingsite/BNxDb8s/Untitled.png (Source) Here you are able to adjust your activity status from Online to Away, which can also be good addition to MapleRoyals. I am unaware if this is possible within the MapleStory code, but I still wanted to bring this idea to light.
Well, current Maplestory lets you do exactly what you are suggesting so, there's that. But yeah, if only it is possible, this would be a great suggestion at least.
As nice as it is, most people make 1 account per char for multiclienting reasons so this wouldn't really help with that