Ok, I get that, but why does Starfleet need the Bandi? They were capable of building starbases in 2-4 years in the twenty-third century (Watchtower-class) so why not in the twenty-fourth? Fifteen years is a long time, and yet you speculate that the Bandi could not have actually put together a real Farpoint station in that time. They could have learned their lesson and traded with local worlds for the raw materials. I would say that the only issue might be the lack of engineers and an orbital facility for major repairs, or would Starfleet supply that?
The Bandi were maybe not so much a need as a windfall. Suddenly this distant world comes along and offers to build a state-of-the-art starbase on the UFP frontier in record time, without the UFP itself having to expend any resources. Even in the UFP's moneyless, replicator-based economy, there are still bound to be some limits on resource availability, so that made it more practical to justify going ahead with a deep-space exploration program way out beyond Deneb (even though there's still no doubt plenty of space between the UFP and Deneb that hasn't been fully charted yet). So the whole idea of an exploration push into trans-Denebian space (or the Cygnus Reach, as I called it in OH and TBA, following the precedent of the Taurus Reach from
Vanguard) was triggered by the Farpoint offer in the first place.
True, it's possible that the UFP could've then gotten around to building their own base and carrying through with the plan. But remember, those "fifteen years" you mention were not a period when the UFP was totally free to direct all its resources to exploration on a distant frontier. Just a year after Farpoint, the Romulans started making threatening noises again. Two years after that, the Borg invaded and wiped out a big chunk of the fleet. So just three years after the Farpoint incident, Starfleet was forced to shift its priorities from far-ranging exploration to building a stronger defensive fleet at home. That was the real death knell for the Cygnus Reach exploration program.