Because I played The Oregon Trail as a child, I greatly appreciate air travel. For a few hundred bucks I can traverse America in hours, not months, with no fear of breaking my leg, starving to death or contracting dysentery. So I consider the hassles of air travel minor, although they are glaring.
The largest problem, as I see it, is a lack of 1:1 storage. The plane is going to leave at the same time whether I board first or last; all I care about is that there's space in the overhead compartment for my rolling carry-on. But just one inconsiderate person with a puffy jacket or a cowboy hat can erase available storage space for his seatmates.
The second-largest problem for me, which is probably the largest problem for the airline, are delays caused by inefficient boarding. Bording the plane from back-to-front sounds, on paper, like it would be the most efficient way. But it isn't. Why not? And what method would be the fastest? YouTube channel CGP Grey attempts to answer both questions here:
By the bye, fans of The Oregon Trail: There's an online version you can play here. Load it up next time you've got a layover at Dallas/Fort Worth.