I wrote a lengthy reply and then deleted it because I realized that I too used threaded email conversations. I think I forgot about them because Gmail doesn't have them, and it's been ages since I used Eudora or Thunderbird. (Or text-only Pine, but I honestly cannot remember if it showed threads).
When they introduced labels they claimed threads were a thing of the past. I didn't even know you could still have them, Google certainly didn't advertise it (since they wanted us to use labels instead).
