Sohcahtoa wrote:Bach's contrapuntal compositions were considered to be old-fashioned in the 18th century, when pre-classical style interested the most. That's it in a nutshell.
It wasn't concidered old-fashioned, but people thought it was to complex, that it wasn't natural (music used to be for people in higher classes only back then, but during that time it was changing, people wanted something "normal", because they were "normal" too). That point of view gave birth to the three styles of the pre-classical period: Empfindsamkeit/Sturm und Drang
(C.P.E. Bach), Rococo (François Couperin "Le Grand") and Style Galant (J.C. Bach). Especially this last style, because of it's "simplicity", appealled to the "normal" people a lot. This style influenced composers like Mozart (who combined Style Galant with bits of Late Baroque).