Let's clear a thing or two up here -
1) This is in no possible way blackmail or coersion except in the lucid imaginations of those that don't possess even a basic understanding of commerce. Gouru, like the rest of the Decal Devs and players PAY a monthly service charge to play AC. When the stipulations or restrictions of what you can and cannot do with that service are changed or become unagreeable to the customers, they have FULL right and authority to voice their displeasure, demand change in said stipulations and/or fire the service. The fact that Gouru and other Decal Devs have contributed their time and resources to make the service an even better value with no compensation coming to them does not change this fact. That leads us to the second thing....
2) Turbine cannot just walk in and 'take' Decal. They cannot just assume ownership of it. For one thing, it's Freeware and Open Source - if they took in a version of that open source and then banned all other instances, that would be grossly illegal unless they offered licsensure buyout from every dev that's ever been involved with the Decal project. While they can selectively and arbitrarily ban and 3rd party add-in they see fit, the legal fallout from taking an open source and making it proprietary technology would be a wide open class action lawsuit that would cost in the tens of millions (see AIX+Linux or SunSolaris v Microsoft).
What Turbine CAN do is ban Decal or TPA's like Decal. The return from such a decision, as they are no doubt aware, would be a drastic and immediate exodus of their subscriber base.
Aside from this - there's no good reason for Turbine to 'want' to take Decal away from the free labor that's developed it. Decal has added features and functionality to the game that has saved what is probably a very large chunk of time and money from Turbine. Moreover, these customizable enhancements to the game is strictly what has retained a large portion of their player base.
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Your side hates my side because you think we think you're stupid.
My side hates your side because we think you're stupid.