1. Because part of the roof is now the door, you can't mount a roof rack or roof-mounted cargo box atop the Model X
2. No door pockets or cupholders allowed. Unless you want those things dumped on the ground
3. They're slower to operate than any manual door
4. You have to stand away from the door after pressing the release button on the door, else the sensors detect your presence and only open partially
5. The doors are incompatible with garages with low roofs. This includes operating the doors inside many/most home garages when the garage door is open
6. Close parking quarters can result in a partial door opening. Perhaps not any worse than a swinging door in this regard. Plus, our Model X has the "summon" function, which helps. A minivan's sliding door, however, will open fully in virtually any gap into which even a slim person can physically squeeze
7. With their electric motors, sensors, additional hinge points, et al,, they're almost certainly much heavier than other doors
8. Speaking of weight: because part of the roof is now the door, the chassis is structurally inefficient and thus heavier than it would otherwise be
9. The operating mechanism is located at the highest point of the car, raising its center of gravity
10. When it rains, it had better be falling straight down, otherwise it's going to blow in through the huge opening and soak the leather and/or your butt
11. Snow on the roof will be snow on your seat
12. Presence of doors in roof leaves no space for a proper sliding sunshade between the "receding hairline" windshield and the door openings. Instead we get a cheesy K-mart-grade fixed sunshade
13. The corner of the articulating door sometimes rests right at forehead height of exiting front passengers
14. The articulating doors are over the rear passengers, not the driver. The rich dude that buys one of these wants to own his Lambo flashbacks for himself, not his whiny kids. They need a sliding door
