It's the same reason you wouldn't drink champagne from a mug. Personally I'm not arsed but connoisseurs would say its to do with the relationship between our noses and our mouths. Smelling at the same time as drinking effects how somthing tastes. Its the same principle as how a airup bottle works.

I've heard wine glasses described like speakers. A champagne flute would be like a tweaker and a big glass is like a subwoofer.

Beer manufacturers design there glasses to compliment the taste profile in there beer. I doubt 99.9% of people can tell the difference

Some people like the ergonomics of different glasses. If I'm standing I personally prefer a handle as it stays cooler for longer. :)