I still use one hand axe outside of Odyssey often. Decimation is a 48-49k WS at attack cap with Sakpata set, AND it SC with SB from COR and BRD. It's still pretty strong if SJ is available and WAR BRD COR all engage on the same mob.
You need the 2h axe to do armor break(very important debuff WS) or multi-step SC on WAR. On DRK if you have 5000 HP boost(1000 TP bonus) active ambu GA Upheaval spam is only about 6% behind r15 Calad AM3 torc spam. But they also SC with COR BRD SB spam, which makes this build viable too.
In other words, you can totally use a different WS on those jobs if you prefer to, and not really suffers from performance loss if you have the setup for it.
I think the main reason why community pushes Naeg so hard is partially because Segment C farm parses strongly favors Naeg/SB spam. And nobody wants to be that guy who lose parse to COR BRD in C and gear shamed. Further more there is an argument that Naeg/SB one shots all mobs on F1-F3 as perfectly geared WAR, pushing more people use Naeg in C farm.
Outside of seg C or bumba I personally don't see Naeg by all end all the best choice ever. It's certainly not the best choice if multi-step SC or piercing dmg is favored.