2X ships were pre-Doomsday, and like the Commander's Edition ISC and Andromedans, they were way over the top. When Doomsday came out, the Andys and ISC were fixed because they were a big part of the SFB universe, while Second Generation X was an optional module that took place years after the rest of the SFB timeline. Our group messed with them once, got bored, and went back to regular SFB.
As for SVC bringing them back, I doubt he will unless there's a big demand for 2X ships, and the added rules that'll come with them.