I did try to do some checking on this a few days back. Long story short, it's actually really difficult to automatically detect that a system is part of a chain in a way that matches intuitive definitions well and isn't really susceptible to missing data messing things up. Still, allowing that some colonisation will have made systems which were originally part of a chain now have enough development around them that it won't be clear which one was the original chain ... maybe around 5-10% of systems were originally colonised as part of chains to somewhere else.
There are probably more posts complaining about people building bridging outposts (I'm not counting yours as one) than there are actual bridging outposts.
The FSD is the most obvious truly revolutionary change - going from it taking multiple weeks for even a fast ship to cross the bubble in 3290 and in-system commuting taking a couple of days, to even an E-grade FSD being able to make the trip in a few hours and in-system commuting taking minutes, and this change coming in extremely rapidly in a couple of years compared with the multiple centuries the same pace of change took on the scale of Earth.
And that's why genuinely revolutionary changes - to which "what if a box, but bigger?" really doesn't count as so I'm not going to ask how the thread got onto this... - don't happen very often: working through all the implications is way too much effort (and in the case of the FSD, one Frontier largely avoided doing either)
SCO in isolation is great - it replaces the boring bits of supercruise which for a decade had been "the most optimal move is not to touch the controls for two-to-twenty minutes" with a hands-on and skill-based way to travel from A to B. It's a far more interesting solution to the "big systems" problem than the average "microjumps" player suggestion, interacts well with the bits of supercruise which were already fun, brings in a much greater variation of ship-to-ship performance in supercruise as well (I don't just mean the difference between new and old ships), etc.
The problem is that it also sticks the final nail in the coffin of the original Elite/FE2/FFE design for trade as a profession. It was only the final nail, of course - supercruise itself had essentially 95% killed it already with no replacement for a decade, so SCO was the right thing to do - but it leaves trade (and other hauling tasks like Colonisation) in a fairly thin spot for game design.
The previous three games had non-optional pirate attacks in almost all systems, and evading or escaping an encounter was extremely difficult compared with trivial. So your trade profit was essentially your reward for surviving those attacks and defeating the pirates (you got token bounties for the kills too, but very much like the few thousand credits original ED also gave). That meant that your trade ship had to consider how it was going to fight off the pirates, and in an insecure system fight off multiple consecutive bands of pirates. A "medium security"-equivalent system in the earlier games would be comparable to a CG system in Open in terms of number of expected encounters (though not in terms of strength of those encounters, necessarily!); a "low security" or "Anarchy" one would be pretty much constant fighting from star to station.
ED broke that - there often won't be a pirate in supercruise, they often won't have time to interdict especially if you're not following the 0:06 Rules For Getting Interdicted book, the interdiction is (easily) beatable if they do, and you can low wake before they scratch even paper shields if that fails. So now trade profit isn't your reward for completing an exciting spacelanes battle ... it's your reward for flying from A to B for a few minutes while nothing much happens. (SCO means that you can pretty much have dropped out at the destination system before any pirate has time to spawn and notice you exist)
And that means that there's not much to do with the "freighter" design space in Elite Dangerous other than "bigger box". The whole "journey-based" gameplay of the original games is dead, replaced with going to specific POIs for specific types of fun. And that works okay for combat or exploration or missions, but doesn't work for hauling because the destination is the "safe" station at each end.
This is not fixable [1], so SCO was a good idea to fix some of the other problems of supercruise instead. But hauling still doesn't really work.
[1] I don't mean that there's technically no way to do it - I can think of fairly conceptually simple ways to bring both interdiction and piracy up to Elite/FE2 levels even with SCO - I mean that the game has spent almost exactly a decade (mid-2015 being the important patch note) committing to PvE combat being optional, and both attracting and enculturing players and designing ships and other game mechanics on that basis. It would be a "revolutionary change" on the scale of the FSD, but taking place during rather than before the game.