Haha I guess I'm (was?) old fashioned too. As you know @HolyPhoenix I've spent a ton of time with phpBB. I was totally going to go forward with BBCode for NodeBB when we first wrote it until @julian stepped in.
Fortunately I'm lazy so he wrote the first MD plugin against my original wishes :p. Worked out in the end though, I'm glad we went this way. As for a BBCode based composer? Totally possible as of recent developments (v0.4.2+), one could potentially write a plugin to modify the composer and such. If anybody wants to write that let me know, I also wrote a BBCode to Markdown plugin which could be useful as well.