Fleet is under attack! [Fleet attack mission]

That's a terrible idea when the whole point of the fleet is to safely buy your items, I don't want some fetch quests or open world pvp while I'm just browsing Kai Zykken. I would be fine with ship to ship combat PROVIDED it was its own instance, but to make fleet part of open world pvp would be a bigger disaster than galactic command at launch.

That's possible?

Galactic Command, the system carefully vetted by a balanced and unbiased committee before launch. Of the six members of the Galactic Command oversight committee, Nem'ro the Hutt described it as "too greedy and money-grubbing", Emperor Vitiate expressed concern that it was evil and selfish, Skadge described it as "overly obnoxious", Darth Thanaton felt it was unfair, Doc considered it to be "a bit sleazy", and Corso Riggs just dubbed it dumb, ugly, and dead.

This idea is not that bad. No idea is that bad, but, sadly, I'm afraid that I think it would still be a mistake, since it and Fleet are a poor fit for one another.

Open world raids on capital and starter worlds, yes, that could be promising, since most story-critical personnel are instance gated anyway, provided that a) it was limited to PvP instances, and b) a bolstering mechanic was tied into level synch in such a way to favour the defenders; so that unless the attackers were really good, it would always be more about "give the newbies a chance to shine heroically defending their home" and less "ooh, let's have fun and gank the newbies and their quest givers!" Giving PVP Jedi Guardians (and others ) a motivation to be on Tython defending it as well, for instance, as well.

Fleet, though, is a functional space, far more a bit of UI dressed up as a location than a part of the story, if you see what I mean. Interfering with it's running would ne more like having a "crash opponent to desktop" PVP skill.

It's not so much that it's a bad idea, so much that Fleet is the wrong place for it.