apy: I have been told by Rabbonim that we don’t hold like that Aruch HaShulchan because we hold those are Birchos HaShevach B’alma, not Tefillos for the Chassan V’Kallah.
DY: I have heard the Ta’ana advanced, at least as a possibility (though not a definite) that now that our women are much more learned and literate it is not as much of an issue of a Zilzul.
charlie:
Which Talmid Chacham instituted Hallel on Rosh Chodesh?
Unclear, but Rava accepted it. So it had the Haskama of Chazal.
Which Talmid Chacham instituted Simchat Torah for the second day of Shemini Atzeret in galut?
Again, this has the Haskama from Geonim and Rishonim. Just because we can’t name the individual who came up with that doesn’t change it.
Which Talmid Chacham instituted not eating kitniyot on Pesach?
Also from the Geonim or early Rishonim.
Which Talmid Chacham added corn (maize) to the minhag of not eating kitniyot?
Again unclear, but it was accepted by the Rama, so it has his stamp of approval.
Which Talmid Chacham instituted men not wearing a talit gadol prior to marriage?
This also has a stamp of approval from Talmidei Chachamim (albeit later ones).