Final answer:
Wolfgang Amadeus Mozart is the most celebrated composer for his popular 'opera buffa'. His works like 'The Marriage of Figaro' and 'Don Giovanni' are prime examples of this comedic opera genre.
Step-by-step explanation:
The composer most celebrated for his enormously popular, though old-fashioned, "opera buffa" is Wolfgang Amadeus Mozart. Opera buffa is a genre of opera characterized by its comedic or light-hearted nature, and Mozart is renowned for his mastery of this form. Among his famous works in this genre are 'The Marriage of Figaro', 'Don Giovanni', and 'Così fan tutte'. These beloved operas combine humor with Mozart's distinctively graceful and intricate musical style, setting a high standard for the genre and influencing generations of composers after him. While other Romantic era composers, such as Brahms, Tchaikovsky, and Wagner, are well-known for their contributions to music, it is Mozart's operas that are particularly esteemed for their operatic humor and wit.