Before I start, this is purely my opinion, based on my experience in the game.
I've noticed several threads about different player groups, who brings Turbine the money, whether a raid is coming with Helps Deep, Kickstarter projects to raise money, etc.
Based on my experience in the game, I believe that "raiders" as a group tend to have more effect on the community, and making the game an MMO instead of just a solo game than other many groups. In my experience, it was people who raided that were usually the leaders and officers of the main kins on the server. Even in lots of the smaller ones it was the same. It was these people who would get groups together for smaller instances. It was these people who would give advice in the global channels. In PvMP, these people would lead the groups on both freep and creep side. A lot of the items on the AH that involved lots of farming (items or crafting materials) would be sold by these people. These people had generally been playing for a long time. Overall on my server, it was "raiders" who formed the backbone of the community.
The length of time these people had been playing for is one of the reasons I think that Turbine doesn’t see raids as cost effective any more. A lot of these people are lifetimers, a large amount of the rest are VIP. I believe that this is not Turbine’s main profit stream. Since free to play, a lot more people have started playing the game. Due to the free nature of the game, a lot of these people don’t play very often, or for short periods of time. Lots of them are also more inclined to buy short term boosts from the store, and other store content. These people are Turbine’s main source of income. They want content that they can complete on their own, and in the short periods of time they can play for. They are also willing to pay to make their time easier.
So in conclusion, while "raiders" may not provide Turbine with the most money, they do play an important role in what makes the game an MMO rather than just a single player game.