Even though there is a lot to be learned in the Litvak world, I think that the essential flaw is making use of Torah for the sake of making a living. But if that would be all that was problematic I would say one could depend on the Beit Yoseph in his commentary on the Rambam where he defends this practice. But where I find the problem is that it leads to the attitude: "I deserve your money because in my merit the whole world stands". I mean, this sort of odd attitude of the religious that they are somehow superior beings that the rest of us low-lives are supposed to support.

[However I must make an exception for the great roshei yeshivot that I knew, Rav Friefeld of Shar Yashuv, and Rav Shmuel Berenbaum of the Mir.--who were really sincere and dedicated to Torah for its own sake.]