Agreed with aesthetics.
Tradition may be a factor. Widespread and affordable glass is a relatively new advancement relative to the span of human civilization using drinking vessels, and plenty of traditions pre-date use of glass. For beer specifically
, opaque vessels can protect beer from getting light-struck (aka skunked).
Brewers and beer drinkers have been aware of the problem of beer being exposed to sunlight for hundreds of years (Corona has forgotten
), even if they didn't understand the chemical reactions occuring. Therefore many beer-drinking traditions/cultures continued to favor opaque beer vessels over clear glass, long after glass use became widespread. EDIT: Remember prior to modern sanitation and drinking water advancements in the mid to late 1800s, people drank beer instead of water and those beer traditions were and still are deeply ingrained in society.