Do you guys think music can only be measured by personal taste? We would be lost if that was the case... I'm not the biggest fan of Mozart's piano works, but I cannot say he sucks. I know he is what he is because there are factors more important than my opinion. It's not the general opinion, it's something much more academical. Beethoven is not a great composer because of Fur Elise, although that is his most famous work for the piano.
An even better example: Chopin. His music is very popular, yet, although genius, he is not in the same rank as Bach Beethoven Mozart. It's not the general consensus that classifies Bach as a great composer, it's something much more serious and concrete.