because EVERYONE Expects A trap. That's the point of traps. Unexpected. I'll push you into a lava pit and see how much you "expected it"
Not trying to be mean, just pointing out what I think.

Why not this if you want your realm to be antisocial? http://minerealm.com/community/viewtopic.php?f=10&t=4338&p=46196

Well of course, but in the event someone attempts to blockade the spawn nether portal, word would get out really fast

This is interesting. It certainly wouldn't be a Mwahahahaha! The nether's all mine!!, but it would still be a completely automated trap that kills anyone going through unprepared. If the fall is great enough, even those not knowledgable of the trap's existence will still die if lacking an ender pearl or the thought to throw it. If the fall is only 23 blocks or so, you can kill anyone without the enchantments to survive. And that means if you're waiting at the bottom, free stuff with no risk of dieing yourself! Of course, there's always those that do drop down and survive and are prepared to kill the looter at the bottom.