One answer might be if you press >> twice accidentally, as it is right now you don't end up going back up the stairs again. This might especially bother someone in the ID, when it means they just lost the level. On the other hand, that's not a really big problem, so I voted for it.
Maybe one thing you could do is bind < and > to a "use stairs" command, and then have "go down stairs" and "go up stairs" commands that aren't bound to any keys by default. Then if a player wanted the old behaviour, they could just modify the .kbd to bind < to "go up" and > to "go down".