The Corsairs and the Outcasts were from the Hispania; between them, they should rightfully have a house of their own. Their RP is based around their attempt to reclaim this; they originally thought it was the other houses who sabotaged their ship, but later found it to be the SCRA, hence the war.
The Corsairs and the Outcasts are two HUGE pirate/smuggler factions; they aren't just pirates, they are nations of their own. Corsairs capital ships arose from contracts with The Order, so there is no issue with the RP side of things.
I'm not quite as knowledgeable in Outcast lore, but its plainly obvious as to why The Order have caps(stolen prototypes).
Other factions have genuine RP as to why they have capital ships; obviously, freelance pirates shouldn't have them and they don't. But the large criminal factions rooted in the major houses have every right to them.
The only question is fleet limitation; however, that doesn't apply to the Corsairs/OC inRP, due to the nature of their resources.
The shorter answer, is no. What would be interesting would be motherships; carrier style, but with working bays and several times larger. Weaponry capped, but potential unlimited. Plus, weakening snubs somewhat; its too easy for a decent powercore VHF to defeat Transports/small caps with basic weaponry.
Bombers however, are fine. Just some more variety in weaponry, perhaps.