I find all this talk about the spiked chain funny. Granted, the D&D spiked chain is not exactly real life usable. But I really want someone to fire of a single magic missle before I listen to that argument with much belief! D&D isn't about reality so much as it is having fun. If I have a player who wants to use one in a game because it'll make his character more enjoyable, I'm certainly not going to say no! I mean, the weapon itself is really not that strong, and certainly not completely worth that exotic feat it takes.
Of course, as long as we're talking about odd things that shouldn't make sense bu we play with them anyway ... let's talk about spiked armor! Come on. They way spiked armor would really be seen by an enemy is with excitement. The spikes essentially provide a guide for your blade to ensure a hit! And that's not even talking about the potential damage that a set of spiked armor would exact upon the armor wearer's assistant and fellow combatants when fighting in tight quarters. Or all those climb and jump checks that certainly a player in spiked armor should be worrying about. I don't find the spiked chain nearly so offensive to my realism than D&D's concept of spiked armor! But then again, if a player wants a set of spiked armor in my game because it helps them enjoy the game, I think that is a small enough compromise that I as a DM am willing to accept. Spiked armor (and all the real life problems that D&D ignores) is not going to ruin my game.
And really, that is at the heart of this thread, isn't it? Isn't this thread at least partially about what parts of our not-real-life-because-its-only-a-game fantasy can we accept? It is a game ... to me broken means it destroys the game. Broken brings the game to a halt until the broken aspect is resolved and brought back in line. But that's just my definition.
In that light ... spiked chains, monks, VoP, psionics, etc do not make my game come to a halt. They do not destroy my gaming experience. To be honest, they enhance it and I am better for them because their inclusion doesn't break my game and it means that my players enjoy the possibilities not involved in other games.