Hmm, sounds good, but you could also turn this question around: if only a few ships had these sensor domes on the outside, why didn't we see them on other ships as well ? The answer to both is most likely, that the generators (or what you may call them) are inside some of the ships. Design is just that, cars for example are also built with different looks, yet you still assume each one has a motor. Although a shieldgen wouldn't be a bad thing to have, either Here's another theory: Stellar, remember that officer saying that they lost their bridge deflector shield after the A-Wings destroyed the domes ? That could also mean, that these domes were just generators, that protected the bridge's superstructure. And regardless, if you're a supporter of Curtis Saxton's ideas or not, Star Wars is GL's project, Warlords is that of eville (who doesn't seem to have email notification for pms)