There is a difference between showing a bright futures and woo woo fantasy. Most people would like to see a more real bright future rather than one so wacky and out there we cant connect.
Yes the federation (on earth) might have eliminated war
Grinding poverty, starvation and improved healthcare.
But there can still be haves and haves not. They just don't live in grinding poverty and on the brink of death.
The haves might be picard with his vineyards and romulan slaves, where as the have nots is a spacey well built house in the desert with full amenities and plenty of food with full access to free healthcare.
There can still be a medium of exchange (currency) without the social and moral bankruptcy of the current economic system.
More likely the romulans in this episode where deliberately infected them with a virus like icheb from voyager )Or picard had planned with Hugh) and sent them out on a suicide mission to get deliberately assimilated to in a attempt to either take out that cube or the collective as a whole.
The virus might have scrambled their brains.
