A pro photographer friend of mine stopped using Tilt/Shift lenses for architecture, he says the image quality is noticeably better if you correct the perspective in photoshop/lightroom afterwards.
But comparing older Canon TS-E 24mm f/3.5, or the Samyang/Rokinon 24mm f/3.5 against any decent wide angle lens nowadays is a wash.
Edge sharpness and barrel distortion? ;)
There’s no logical reason why a TS lens should be sharper at the edge of its (moveable) image circle than an ultrawide should be at the edge of its fixed image circle. They both offer around the same angle of view, just at different focal lengths.
But I think your pro photographer friend is right. Modern DSLRs and a really good wide angle (say 9mm or 12mm) will let you correct in post for any shift you want.
Tilt is still not possible even in post, but I found that to be rarely useful at 24mm. For macro it would probably be useful all the time.
I occasionally wish someone would make a camera with a circular sensor that captures the entire usable field of view from the lens. If nothing else, a professional camera like this could skip the extra side grip and save some bulk because there would be no need to ever hold the camera sideways.
I've had the same thought, though I wanted just a 1:1 square camera sensor. It could perhaps be "oversquare", so that the corners are slightly rounded off. That wouldn't be so wasteful, since a sensor needs some shaded pixels to measure noise anyway.