There has been a directional blur for this very purpose for many many years. “Flicker Filter.” All it is is a vertical blur. It can also be found within the deinterlace filter.
However, adding your blur in photoshop will reduce renter times substantially, since FCP is rendering the motion blur every frame. It’s much easier to right click and say “open in editor” (photoshop usually) and add a little directional blur and save.
Many will notice that in the universal binary user prefs there is now a check box to “auto update” linked files. So you’ll never get the relinking dialog when updating externally linked files. Very nifty.