For me, it isn't the cost or the slightly underwhelming firepower.
It's the huge chunk of points that aren't available to you from the start of the game that, at best, are going to show up and start affecting things in full by turn 3 for arguable gain. The issue is really rough when you see them loaded with a close combat squad, since it's always a hassle.
Like Slips mentioned, if you're sold on arial transport, I'd go Kharyibdis. Or dreadclaws, those are always a blast.