Part of it is personal preference, part of it is me not wanting to alter my workflow, part of it is the specific desire not to have to have Yet Another Piece Of Separate Software (sticking my head in the sand and ignoring the fact that a firefox extension is a separate piece of software), part of it is anger that WinSCP doesn't support normal FTP operations, but mostly it's that I think Firefox has matured to the point where it should be able to provide me all of the functionality that IE did, and this is simply something IE could do.