I disagree. I think square-er frames have been used beautifully, not just in the past, but even in recent years. Recent academy ratio films like Meek’s Cutoff, Fish Tank, American Honey, Ida for example. And the IMAX 15/70 format can be really impressive. If you get a chance, find an IMAX screening of Dunkirk this summer, that’s 80% IMAX apparently. Where I do agree with you is the misleading use of the “IMAX” brand to sell seats to 2K digital performances, which are rubbish. They’re confident that the younger generation are sufficiently confused about the distinction between film and digital that they can use their ‘gold standard’ name to market a whole range of sub-par products.
I also agree that Star Wars is an odd choice for IMAX 15/70. The open matte 15/70 sequence in TFA was gone in a jiffy and few people noticed. It was edited too quickly for it to be visually worthwhile. Plus Star Wars is a cinemascope property - it’s a strange choice to shoot chunks of it in 1.43:1.
I am however, happy that it forces Disney to release the films (in a few cities at least) on celluloid. That’s a good thing. They should consult Christopher Nolan on how to avoid digital intermediaries between the 35 and 70mm camera negatives and the release prints, so we get something that (vfx aside) hasn’t touched a computer. If they’re going to use full 15/70mm they should also talk to him about how to shoot action sequences a little slower so that massive image isn’t wasted.