Paul,
The Road Hole, unless you happen to be an elite tour player and playing in the British Open, plays at a maximum length of 455 yards. It's status as a par 4 has nothing to do with any attempt to convince the golfer that it's a tougher hole than it really is, but rather just a reflection of the fact that it measures less than 475 yards, that being the standard length over here at which a hole becomes a par 5. Historically it was a par 5 because, in an era when the ball just didn't travel so far off the bat, the yardage at which a hole was deemed to be a par 5 was less.
More broadly, regarding your point about the golfer tending to treat a hole differently because of the number on a card, I'm all in favour of holes which muddle the players' thinking. Learning to think about your own game instead of the printed par is all just part of the joys of golf for me and something everyone should be made to consider more often, be it in the form of an unreachable par 4 or a par 5 which you should really be treating as a par 4. It's a skill which you'll see the best players in the world apply all the time as second nature; doesn't matter one jot whether you put a 4 or a 5 on a card, if they can reach in two blows and they make five, as far as they're concerned, they've dropped a shot to the field.
Late Edit: Having written the above, I hit post and discover BCrosby has summed it up far better in a few short words than I could manage in an entire ramble!