Upper tiers of an action (such as Fire II and Fire III) will be abolished.....

[Betelgeuzah]

ok but what about nuking?
shouldnt choosing which strength of nuke to cast for enmity and MP consumption reasons fit into that? or is it really so much so that Nukers dont and shouldnt effectively exist in the FF MMO franchise but in every other game?

To be fair, nukers haven't "effectively existed" in any FF game other than 13 so far. In any other game they have become inferior to melee DPS sooner or later.

The only reason to use them would be if you don't mind being less effective. That doesn't work in MMO's.