This phone has the highest screen area to weight ratio except for the Galaxy S25 Edge.
They want thin phones for the same reason they like fast cars. The same reason that ice cream tastes good.
Why do (some) people like jazz music?
Aside from a tiny amount of nerds needing post hoc rationalisation as to why they blew $1500 on a gimmick, absolutely nobody will go looking for a phone and consider grams/mm² as an important measure.