I dislike Eureka too. But in my opinion, the fault does not lie on Eureka itself. In my opinion Eureka is only a flop because the Dev Team didnt think of more content to do inside it. People already gave really good ideas, but yet they are staying adamant on their decision. It would be so much different if you could do daily quests, weekly quests, maybe add something instance wide people can work on? Like a Players vs Beasts, while you have to defend your base? Or simply do invasion times where mobs invade certain areas/aetherytes. Or why not implementing the Hunt in Eureka as well, instead of killing mindlessly mobs just to stack your chains. (and Im not talking about S/A/B ranks, I mean just kill 5x XXX mobs to receive your reward etc).

But there is indeed 1 fact that people should not forget. Eureka was a "big" announcement during the FanFestivals. And when you buy an expansion, its the same like buying a "ticket" for future content.
That ticket should grant everyone to find something they can enjoy. That ticket exists because people want something new, fresh, innovative. Beside the MSQ and new maps, the new beast tribe and new primals, every content is same and dried out as ARR and HW. Eureka could of been the one flower in the hopeless desert, yet all they did is a reskinned Diadem (except you have to kill regular mobs actually too to spawn FAT- erm, Notorius Monsters).
While I still think Eureka could of been THE content, they did not think thorougly enough to make it enjoyable.