It isn't an assumption, it's a valid observation. if EA/BioWare thought they could make a lot of money on a Mac client, then they would have developed one already. I work in a software company too, and shockingly, we build the software that we think people will buy...
So I think it is far to assume that if there is money to be made with a Mac client, it isn't enough to have been instantly compelling, and Mac people shouldn't be holding their breath for a mac client.