The main problem I have with it is just that, it doesn't really give you any control and it tends to cause people to dive into private groups. I've been battling a large player faction for a while, but haven't seen a single person. The general consensus is that the artificial injection of a ton of player minor factions is what largely killed Colonia.
Not being able to directly control a PMF is not really an issue either, at least not here. The Lore here is set up that the PMF is the government while the Wing acts as a Black Ops that operates behind the scenes to make them goals come to fruition. And if PMF one day get a change so that you can directly control it we can incorporate that.
I can't say anything about the BGS driving people into PG, for our Wing doesn't have any restrictive policy in that regard. Open is encouraged, but PG and Solo are also choices that the game offers and thus are not frowned upon. Besides, forcing to play people in one version only is against the spirit of the game in the first place.
Even if we'd have only Open available that still would mean you have no visibility if you and your opponents are not on the same platform (PC / XBOX / PS4). Let's not start about the instancing and ability to block people in the game which makes them literally invisible as well.
It is quite logical that a small area that is overly populated by people who pursue the BGS will have results showing you won't get anywhere else in the game. Best comparison I could come up with is a piece of land that dozens of Farmers want to use for their own purposes and thus start to irrigate and prepare their portions. But soon those areas are too small and you want more, resulting in moving to the patches of the others and fighting ensues what to plant there.
The bubble is densely populated as well BGS wise, but here at least you have places to go when expanding. Colonia is too restricted in that regard and can be seen as an experiment from which FD hopefully learns how not to do it again.