lesschumras: “I’m just curious, then, why we imitate and continue here what worked well for them ( chalav yisroel, kitnyos,) and instead now decide the best strategy for our current situation.”
Valid question. Chalav Yisroel is a gezeira from the time of the Mishna, and the rule is that a gezeira of Chazal is valid until eliminated by a more significant Beis Din then the one that enacted it. Kitniyos is a much later minhag, from the late Ashkenazi Rishonim, and never had the status of a gezeira. However the Yaavatz writes that as much as he would like to do away with what he considered an illogical chumra, he was not willing to uproot a long standing minhag paskened in the Rema. Additionally, I have heard from a Sefardi Rav active in the kashrus field that the original issue of kitniyos is alive and well today. He told me that he went to inspect a soybean oil factory for Pesach and found every single sack of soybeans contained numerous grains of wheat.