It is a shame we probably won't see it on the big IMAX screen. But apparently IMAX film aspect ratio (1.43:1) is actually closer to 4:3 (or 1.33:1) than scope (2.39:1) or HD (1.77:1), so showing the home version in 4:3 avoided more cropping that would have been required if they had opted for a widescreen presentation; it's actually closer to the ratio it was shot in. This is according to Snyder's wife and producing partner, Deborah Snyder. The details are explained in this link, though I think the author is overstating the aesthetic power of 4:3 for Snyder's vision. (Of course, this all would be moot if Snyder had shot the film in scope ratio, instead of IMAX, to begin with.)
4:3? Good by me!
collider.com