Sometimes there are other things to squeeze in a bag besides a laptop.

I guess you adapt to whatever you've got, but at this point I'm spoilt by being able to easily slide my thin laptops in and out of my backpack. Makes going through airport security that much easier.

Aesthetic? That feeling that we're in the future and this isn't grandpa's laptop? Some other intangible quality from which I derive subjective satisfaction?

That you can fit your laptop into a bag doesn't seem to me to be a reason to be happy with thick laptops.

Because thinness tends to correlate with lightness in laptop designs.