What color stripes are on a tallis also has nothing to do with Halachah. Yes, it is correct that there are plenty of minhagim that have nothing to do with Halachah.
However, as for those that do, it’s not because one side is going against halachah and the other isn’t. There can be differing halachic opinions without it meaning that one is “trumping the halachah.”
Also, I thought somebody mentioned on another thread that the Rema considered Kitniyos fully assur. I really don’t know enough about that to weigh in, but if anyone else does it would appreciated.