Avira, the Vilna Gaon wrote that his two biggest regrets in life was his failure to 1) instate saying Birchas Kohanim during the week in Chutz L’aretz and 2) end the cherem against polygamy.
Rav Avigdor Miller also said (it’s available in his voice on his tapes and is printed in one of the recent Seforim from him) that if the Gedolim today thought it necessary, they could end the cherem against polygamy.
Also, Avira, regarding your second point, if a girl was (say) 45 years old and never married despite trying hard (as so many r’l are), I think a nice number of that demographic would consider it if it were acceptable in Yiddish society.