I disagree, I don't think this is purely aesthetic.
What follows is just an opinion:
The smaller you make the package, the harder it is to do active heat management with fans and big heat sinks. Apple spends a lot of R&D dollars on reducing the power usage of their computers - Macs are way more power efficient than their competitors.
Thinness is the authentic, unfakeable, consequence of all of that power management engineering. Competitors can't copy the look of an iMac without also investing heavily in design work to reduce power consumption.
In an ideal world, Apple could just publish power usage figures, but that doesn't really sell computers outside of the data center universe. Thin computers on the other handle are much more marketable, so Apple is using thinness as a marketing proxy for power efficiency.
What follows is just an opinion:
The smaller you make the package, the harder it is to do active heat management with fans and big heat sinks. Apple spends a lot of R&D dollars on reducing the power usage of their computers - Macs are way more power efficient than their competitors.
Thinness is the authentic, unfakeable, consequence of all of that power management engineering. Competitors can't copy the look of an iMac without also investing heavily in design work to reduce power consumption.
In an ideal world, Apple could just publish power usage figures, but that doesn't really sell computers outside of the data center universe. Thin computers on the other handle are much more marketable, so Apple is using thinness as a marketing proxy for power efficiency.