Mages / Supports whose ult do not cost 100 Mana

I remember there were a few patches that mentioned "modernizing" the mana costs of Ultimates, by making the vast majority of them 100 mana, especially for the support class. Mages seemed to have been affected similarly. As it stands now, several mages/supports still have R mana costs that are above 100. This includes: Karthus Orianna Twisted Fate Zilean Zyra Was there a reason that these fellow champs were left as they were??