IIRC, Rhino paid attention to the mouse pull direction with Extrude up to Rhino 2 or so, then it was changed to the current behavior - for the inverse reason of Tony’s, i.e. people that simply wanted to extrude and type a value without having to pull the mouse in the direction they wanted it to go. Because if pays attention to the mouse cursor in that case, half the time it will be wrong as well…
–Mitch