One could (but shouldn’t) argue that, thanks to clocks, we shouldn’t have to keep a second day of yom tov in the exile. Obviously, this argument would be absurd and laughed at. It is beyond my comprehension why people don’t treat avoiding kitniyos with similar gravity. We don’t logic our way out of minhagim.
Sometimes I tell people that the one positive thing the Conservative movement has done is served as a warning against this logic-based heter creating. The Conservative movement in America just “allowed” kitniyos. Now there will be people thinking they can just buy a bag of rice and call it a day, not realizing how much effort and care Sphardim put in before they eat kitniyos.
I read in an old halacha article here on YWN that one source says that not even Moshiach will have the authority to undo the kitniyos minhag. Does anyone have that source?