Thickness matters because the tray table and seat back of the seat in front of you are usually at an acute angle. To get a good viewing angle the screen needs to be open to an obtuse angle. So the top edge of the laptop lid and the seat back will often be in contact to make a comfortable viewing angle, especially if the person in front of you reclines their seat. The thicker the laptop is, the higher the hinge sits. The higher the hinge, the higher the top edge of the lid. The higher that is, the more of an issue this becomes.
Imagine that purple is the tray and seat back, and green is the laptop.
You have options - if the screen is smaller, it’ll be less likely to hit. If you slide the laptop out, it gives you more space. That cramps the wrists if you’re typing, though, and eventually it’ll hit you. Making the laptop thinner gives you more options.
Thickness matters because the tray table and seat back of the seat in front of you are usually at an acute angle. To get a good viewing angle the screen needs to be open to an obtuse angle. So the top edge of the laptop lid and the seat back will often be in contact to make a comfortable viewing angle, especially if the person in front of you reclines their seat. The thicker the laptop is, the higher the hinge sits. The higher the hinge, the higher the top edge of the lid. The higher that is, the more of an issue this becomes.
Imagine that purple is the tray and seat back, and green is the laptop.
You have options - if the screen is smaller, it’ll be less likely to hit. If you slide the laptop out, it gives you more space. That cramps the wrists if you’re typing, though, and eventually it’ll hit you. Making the laptop thinner gives you more options.