Even though I took an extended absence from Disco, I'd like to pitch in with my own observations.
First off, I think there's a definite correlation in the gallic expansion and the movement of the player base. People have often complained about how nearly 100% of server activity seems packed into the omicrons (namely omicron delta and the surrounding systems), and they're always wondering why we have so much activity in eastern/southeastern sirius rather than where all the mod updates are happening. It's pretty obvious to me: anything to do with gallia pushes people away. Players want to be as far from that clusterf*** as possible, and that's the omicrons. Now, I'm not complaining, as it's given a huge boost in activity to the factions I always played for the most (Order, Core, Nomads, etc.), but at the same time I can see a definite negative impact on the mod as a whole due to the changes that have been made in the name of 'story advancement'.
Bretonia has, obviously, suffered the most, along with the whole slew of tau systems. Back before gallia was introduced, I frequently flew through bretonia, kusari, and the tau systems on my smugglers and traders. Now I can honestly say that I havent taken a non-combatant ship into that entire area of the mod since like 4.84. The taus have become anathema to trade routes, kusari was made hostile to junkers via the rep hack, and to top all of that off mining completely snuffed out any form of trade or smuggling as the most profitable pastime. Mining routes should never have been made 2-3 times (or more) more profitable than the classic smuggling routes, as those killed of a LOT of trader interaction.
On the topic of mining: piracy doesn't even really happen anymore, because it's far more profitable to be a miner or a transporter and it's simply not worth anyone's time to actually try and catch the transports anymore.
The entire concept of gallia has -always- felt forced by the dev team. Nobody really wanted it to begin with, and while in the first iteration gallia was a nice little novelty (and might have even helped junker activity following the kusari repnerf due to gallic connections), it quickly became an area that nobody wanted to deal with. Gallic systems are convoluted and hard to navigate, there are no decent trade routes between gallia and sirius - and even if there were the rep of the local factions would probably nullify any attempts at trade. Junkers quickly lost any kind of connections to gallia as they were outed by the government and basically snuffed out of existence, and that to me felt like a forced play by the dev team to try and cover up some apparent mistake they made by including junkers in gallia at all.
What's worse is that gallia, despite the constant defeats they've suffered during player events, and the fact that they're completely outnumbered by the houses and their own rebel/criminal/terrorist factions, somehow manage to keep pushing forward relentlessly, wrecking everything in their path. Leeds used to be one of the most frequently traveled systems in the mod before gallia made their way past the taus, and now it's completely dead. The same is going to happen to new london, and eventually the rest of bretonia. I almost get the feeling that someone (or multiple someones) on the dev team simply have a bone to pick with bretonia and want to wrecking-ball it out of the mod entirely. It's bad enough that they've got some of the ugliest vanilla ships and have always struggled for activity, but now everyone seems hellbent on destroying the entire house.
Gallia needs to go, it was a bad idea and always has been a bad idea. Stop promoting it, stop trying to force it into getting activity, just wipe it out and be done with it. Discovery was better before gallia came along.