Hi! Yeah, of course for the most of people it's more convenient to always download files sequentially, but I haven't put this option in the Preferences dialog on a purpose to force users to enable it only when they really need it. The sequential download is very bad for file sharing - BitTorrent protocol is designed it such way that peers always try to download rarest parts of a torrent to help spreading of the torrent, and the sequential download breaks this idea.