This was my exact thought when I saw Agent class story on Quesh. I hate that planet, main storyline seems unfinished, none of quests there ever gave any affection to any companion I tried, so I always assumed it was just extra thrown in planet.
But Agent is only class that can't go on without that quest, and that quest has real reasons to happen on quesh.
So it seems quit likely that this whole planet was created primarly for his storyline.
This is another thing that pisses me off in other classes. Multitude of companions that are here because they have nothing better to do, or simply because they are military and were assigned here, but aside from that have absolutely no reason to be here.
But fact that Agent has hsi whole crew reasonably involved in his story is another piece of "got more work done on it"
It's not that other classes are bad, but when you see how much better they could have been, yeah. Not nice.
This is even more proof for me for my "favouritism" thesis.
They could at least have exchanged ideas among the writers.
And, yes, a whole planet created exclusively for one class ? If not, then either the writer was very good or the other writers were rather bad, in terms of integrating a story line into a planet (or vice versa), but in the end it just makes me angry.