So yes - clarification is needed. I'm willing to take on faith that there is measurable degradation of film quality. Let us grant that there is plenty of empirical evidence for this claim.
There is no empirical evidence presented besides blog comments that this measurably effects the greater portion of hedonic goodness in theatre goers. Worse - I see no presentation of empirical evidence whatsoever for Ebert's larger thesis that the degradation is sufficient enough to have a measurable effect on market share (as against dvds etc). Bearing in mind they were losing market share before 3d.
Hence there is no pragmatic reason to be upset beyond perhaps you're own heightened sensitivities - which Ebert himself may possess - I have no idea.
In any case - it's an extremely poorly argued article.
But it is truly weird - People just love the Ebert.