Of course Enderman xp farms are an exploit to the spawning mechanics, but isn't minecraft one of the only games that exploits are studied as if science.
Practically half of redstone theory could be defined as exploits or bugs that have been left in the code for the benefit of those who use it, without the exploits many of the logic gates would not work, BUD switches etc.
For me half the fun of minecraft is discovering strange game mechanics or "exploits" and harnessing them to give me an advantage.
While many many many games are studied for weird bugs and exploits, they are often embraced and accepted. In StarCraft, for example, there are a shitload of known oddities that were discovered over the years, and many were deliberately coded into StarCraft II.
In Minecraft, there are indeed many good oddities. Our point, however, is that Enderman spawners are problematic for the economy/fairness/spirit of VC. We removed the selling of pearls, people bitched, and now they are back at a low price. The interesting thing about the spawners is that Mojang doesn't like them and is thinking about patching MC to make them much less "Overpowered". Mojang isn't exactly efficient, so who knows when that will happen.
I do not agree that the XP attained from the Enderman farms are giving the users an unfair advantage. Those who gather the resources and put their time and effort into building the farm should reap the rewards.
Saying that this is unfair is like saying those who research and put time and effort into gaining an advantage in sports is unfair, with the example of cyclists or auto sports using modern materials such as carbon fibre or fibre glass. It is up to those who want to "compete" to follow the leaders and use the new technologies.
Some of us think the argument that you put "time" into building the spawners means you deserve to reap the rewards is missing the point. It's not like putting the time into making carbon fibre for a racecar to go faster; it's like putting time into developing a microchip that exploits a flaw in an ATM and pours out unlimited money.
I do however agree that the economy alongside the Enderman farms unlimited supply of ender pearls are being abused, mainly by 1 person.
Regardless of how many people are exploiting them now, I think protecting the spawners will only increase the amount of people exploiting them.
And we all know the person that yearns for a virtual wealth that cannot buy him much more than cooked porkchops or wood logs from the market.
Personally I am not too found of the economy system, I prefer bartering and trading but am unsure how practical this is in a large server as I have never seeen any server carry out this method of an economy. Most servers believe more plugins attract more players.
While I sometimes wish we had a bartering system, but I don't think it would be very good. The most we can do is make certain materials not for sale in the market (There already are some).
Honestly, my only suggestion would be to remove the selling of enderpearls completely and a complete economy reset, everyone starts from zero. Admins included.
Removing pearls is an option, but resetting the economy? That's pretty extreme... though interesting.
Thanks for the comments