Near as we can tell, the planets that make up the Future Fronc, anywhere from 7 to 11 planets, were largely already colonized but at such low numbers as to not be admitted in their respective nations... like any other frontier town that might see a jumpship once a year or two. Their populations dropped from the 2nd SS war era (when they were fought over) to the point they weren't even mapped.
Maybe economic reasons
Maybe increased piracy
Maybe loss of jumpship trade
Maybe loss of technology (power, water purification, etc)
The whole formation of the NCR was a government movement to provide law and order, protection, and development on those worlds. The Colonial Mashals were deployed, mostly in lance or single-man formations, to protect locals and provide order. They were supposed to be built up to the point (theoretically) that they were 3000's era lance-company sized units with bases and normal podunk defenses... and come together as a band of merry rascals to go rassle up suspected pirate bases.
Decent new mechs plus militia armor is a good enough deterrent for the typical (lance to short-company) pirate force, equipped with decrepit 3rd SS war era mechs.
Essentially they were meant to drive off pirate gangs from the region, affording growth and development. It might even be politically motivated to drive pirate groups into the less-well-defended Far-Looker colonies... but that's pure speculation. The MoC outlands were fairly well defended, albet mostly because they lacked good transport assets at the time.
For rarer info on the NCR, look into Shattered Sphere. There's also Periphery 2nd (man in swamp) for the best info, Historicals: Brush Wars gives good info on the area, and the Marshal writeup (which is in Periphery 2nd anyways)
