It used to be that fishermen thought ferrules negatively affected the action. There were even 1 pieces, but most were 2 piece.
That seems to have changed. Better ferrule design, or just a change in mentality, or perhaps a bit of both.
FWIW, almost all of my rods are 2 piece. No particular reason, just thats how it ended up, I wasn't avoiding or aiming for any particular number of pieces. I don't find 4 pieces to be any incredible advantage as far as carrying and storing, my car handles the length of a 2 piece just fine, and when carrying, I carry it as a 2 or 1 anyway cause I don't take the case out of the car. If there is a real advantage to 4 piece, I'd say it's probably air travel. I did just pick up a 4 piece and it casts just fine.