I.. would disagree with that assessment.
In Heavensward, we got:
Flying (and new mounts

)
Expanded MSQ (which is a lot of content on its own)
Higher level cap (50 - 60), which SE likened it'd take the same amount of effort as 1 - 50.
Expanded jobs
3 new jobs
And a plethora of other things.
Yes, the endgame is sparse. However, do people not understand how sparse 2.0 was as well? All we had for endgame was.. The Binding Coil of Bahamut at the time. Turns 1 through 5. Unfortunately, the story was also locked behind raiding. There's more middle end content from Heavensward than there was from 2.0. Wait for the content patches. It'll be filled out more.