Most of the published missions are rather "meh".
I think that's a bit harsh. The three included with the core set were necessarily very limited to the ships available in that set. I remember playing the Senator's Shuttle scenario for the first time and thought it was pretty cool, Of course we have all moved on, and those missions must seem very "meh" to most of us now, but they were a good and quick intro to something beyond the Deathmatch. And remember, back then they didn't really have a clue that this game was going to be the runaway success that it is, and probably didn't think it worth much effort to come up with intricate scenarios for a game that may not be successful.
The missions included with the Falcon, Slave, and Shuttle were designed to showcase each of those models respectively, and I thought included some interesting elements without requiring a massive investment in the game. Mission 7, that came with Imperial Aces, is the one I thought started to break the mold a bit, and I really like the direction that things are heading with the Transport campaign-style offerings and the Corvette's branching story lines. It says to me that they are paying a lot more attention to the non-competitive, storyline mode that many have asked for, as evidenced by this thread and the discussion it has sparked.