My recollection is that one reason given for not increasing the system to J-6 was that the average jump range wouldn't go up enough to justify the increased cost. Personally I think that is just the official line for public consumption and the real reasons are a desire to retain the governmental/naval and megacorporate speed advantage, and also resistance from vested interests - a lot of worlds along the X-boat routes would wither if they were moved, which they would be if a J-6 system were set up, even if the J-6 system only covered the main trunks, leaving the side branches at J-4.

Yeah, look at what happened, for example, to Route 66 as the Interstate system came on line, ( repeated all along the Interstates where whether a town lived or died depended on where the Interstate exchanges went. ) Lots of ghost towns along that route. There would have been enormous resistance to disrupting the status quo.

Also, building the original XBoat routes at J4 must have been rife with speculation and chicanery, much like the building out of the rail system in the US during the 1800’s.

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Except that it's already been posted that the Xboat system was actually originally built at J3 & then upgraded to J4, which means that the 'US Freeway System' experience has already occurred.

(In any case a small town can't really be compared to an entire star system. If the system only existed cuz. an Xboat station had to be there then it wasn't a very important one anyway, just as those dinky little towns in the US weren't. And if they aren't important then few will care. However, the Xboat system has lot's of J1 & J2 zigs and zags & I don't think that would change much cuz' it obviously didn't when the system went from J3 to J4. The main purpose is to speed overall commo time from Capital to Regina &  that can actually be done w/o even upgrading all the individual Xboats. Heck, there could even be the equiv of the old USPO surface vs airmail system which, I believe still exists in some parts of the world)

However, considering that it's also already been posted that the avg jump is only 2.6 parsecs, it would seem that a lot of 'slack' was retained. In any case the Xboat system is not a transportation system like freeways but, primarily, a commo system more like a post office system. Also, just like everything else there would be just as many, & just as powerful advocates for as against the upgrade. It could easily already be in progress in selected interior sectors, perhaps still in prototype mode due to problems encountered with the required drop tanks or with refitting the Xboat design with J6 drives. (Just how much more Dtons would be required for the Jdrive?)

p.s. we also know that drop tanks, despite the disaster reported by the TNS, didn't go away. They certainly stayed around.