Since we do not get any new transport-possibility, as in flying, swimming... and also no content like Eureka being announced during the Fan Festivals, there is simply not much being offered in this expansion

The same things as in:
2 new jobs+level cap increase
New Zones, New Story
New Beast tribes + new primals
New 24 man raid + new 8 man raid
and few QoL stuff like New Game + (which I doubt will take to many resources, as in create new maps etc)

I could imagine that they worked on 2 races - as they had not to work on new eureka-type content or working on swimming on all areas (+the ability itself, implementing it wisely into the story, etc) which would usually eat a lot of development resources. Meaning, more time for a second race.. maybe.