Comment by beloch

Perception is at odds with quality sometimes. For headphones, lighter is better even though people often perceive denser objects as being of higher quality. This is why high-end headphones often contain a fair bit of plastic, but also make sparing use of light-weight metals such as magnesium in the places where strength is especially important.

These Airpods appear to have ear-cups made entirely of aluminum, which is an odd choice. Plastic cups are typically more than strong enough and aluminum is actually a fair bit denser than magnesium. That's a lot of weight for no good reason. Aluminum is a great material for some things, but Apple seems to be using it for everything even when its not appropriate.