After his death, Bach's choral works were dismissed as old-fashioned for decades.
After Bach's death in 1750 his music was deemed old-fashioned; his great choral works went unheard outside Leipzig. Only in 1829 did the 20-year-old Felix Mendelssohn conduct an abridged St Matthew Passion in Berlin, its first performance outside Leipzig. That sparked the 'Bach Revival' that made him a foundation of classical music.
Useful: Fame in one's lifetime and importance in history are two different rankings.
Source: en.wikipedia.org