I have to completely disagree. I DESPISE the parking structure. It never fails that they park me in the farthest back corner of the garage, which is about 6 miles from the tram. So after the 3 hour hike to the tram, you then wait in a line for the tram, ride the tram, and then get dropped in Downtown Disney, which I feel is much further away from the park entrance. (Strangely, you say the opposite. Maybe it's mental.) And I feel like the lines at the end of the night for the tram are horrendous compared to the busses. It is certainly more claustrophobic.
In contrast, the bus parks right next to your car and drops you off close to the park entrances. Way easier than walking 6 miles across the garage. And there's never a wait to get on the bus at Toy Story, but there's almost always a wait to get on the tram at the garage. The actual bus ride is kind of long, but I still prefer that over walking across the garage. At night the line does get long at certain times, but we've learned to avoid those times. I think the longest we've ever waited for the bus during the busiest possible time is 10 minutes.
I don't think we've used the garage in years because we prefer Toy Story so much.