Sorry, but I can't see why a paladin couldn't get away with this. For example, party is going down a dungeon hallway, encounters guys coming their way. Paladin marks, sits back and uses a bow. Fighter and company are up front holding the line. Not very easy for the enemies to get past the front line, and the paladin's not being a coward, he's just holding his ground doing his damage. Seems reasonable to me...and as others are pointing out, may be even more useful than a ranger's attack.
Now sure is this combo going to work in every situation? Of course not, but on the other hand if the baddies charge the paladin its not like the party is screwed. The paladin for all of his "strikeresque" feel with this combo, is still a defender, with big HP, big AC, and the ability to heal himself. If the baddies come his way, good for the party. If the enemies stay away, good for the party. Its a win/win situation.