Aliya LiRegel was really meant to be on Rosh Chodesh and Shabbos as well, but it was not commanded because there is a need ‘to see’ (not only be seen) in the Beis Hamikdash. the ability to see Godliness on Shabbos won’t happen until Moshiach comes, because Shabbos is ta’anug (delight) which is too subtle and ‘hidden’.
