I balk of time likely went towards stability. Bear in mind, Eureka requires multiple instances which must assume 144 active players at all given times. That is no small feat nor can they merely copy/paste the code once one instance has been thoroughly tested as they now have to test multiple ones on the servers themselves. Many Notorious Monsters also appear wholly unique in design. They have said previously new gear models takes upwards of six months. So I imagine monster design falls in that category somewhere. Someone mentioned earlier Shirogane may have played a whole it Eureka being delayed... which makes sense. It's very unlikely they intended to add six additional Wards and overhaul how house purchasing works so quickly. The enormous backlash forced their hand.

This all being said, I am not defending the ultimately shallow beginnings of Eureka. They should be well accustomed to their limitations and not release content half-baked unless they intent to be candid about it.