One of the reasons that Manticore has Junction FORTS instead of a fleet of hyper-capable ships guarding the Juntion and each of the known termini is that you can pack more defense and offence capability into each fort since you leave out all of the hyper-drive eqipment. You can also use different geometry on the forts since you don't need to allow for the drive.
Another reason is that you can't just divert the forts to another location and use them in other systems. They HAVE to stay relativly near the termini they are to defend and not get pulled out of position to engage hopping systems and hyperspace flight. While this does limit your ability to reorganize you defense (in the whole system or transit to another location) in the short term, it does make sure that your wormhole point-defence stays where it is needed.
The Juntion Forts are part of a layered defence of specific key points for Manticore. If you start pulling that away, you lay everything open to trans-wormhole assault and ending up with the attackers comming though. Once you lose the Junction you are in really deep crap.
Forts are tough. Forts are highly automated and use fewer personal than hyper-capable ships for their size. They are also very large and along with having more capacity to carry weapons, they can have both larger weapons and deeper magazines. Depending on the current philosophy, they each could also have their own squadrons of LACs which would both thicken the defense and provide for more flexible offence.
As far as the wormholes taken in Lacoon II, there is little reason to and a lot of reasons not to transport Forts to them. Mostly it is because of lack of mobility on the part of the Forts. To this point we have NOT been told that Manticore intends to hold onto those wormholes. It does not make tactical sense to move Forts to places that are likely be either abandoned or (hopefully) turned over to a sucessor government of the local system once the OFS or similar management is deposed.
It should be assumed that the SL, at least, is likely to try and re-take at least some of the wormholes and a for would have to be abandoned- under fire- and scuttled. You don't want any of the new tech falling into SL hands and you don't want to set up the situation where you have to leave the crew behind because the Fort can't hyper-out. With full-up warships, they can fight AND can leave (unless crippled) either thorugh the wormhole or into hyperspace. While the forts do have in-system impeller capability, they can't run anywhere. The alternative we have been shown is parking one or more CLAC at each end of a captured wormhole to provide deeper defence/offence capability.
