As ever, definitions are in order: Nearly every work of art is in some way “formulaic” in a broad definition of the word. If “paint on canvas” is a formula, then all paintings are formulaic. If “words on paper” is a formula, then every novel, poem, or essay is formulaic.
In less obvious and more meaningful examples, the sonnet is a form: Should one dismiss every sonnet because it is formulaic? The landscape or the portrait is a formula: Should all such paintings be dismissed?
Some critics dismiss the waltzes written by Johann Strauss II as formulaic. He composed more than 100 of them. But could ‘formulaic’ be in some sense a virtue rather than a vice? The composer found a way to create music in a pattern; this is perhaps an achievement rather than a crime.
Shakespeare wrote more than 150 sonnets. There are certain similarities among them. Should they all be dismissed as formulaic?
So also with the more than 130 marches composed by John Philip Sousa.
To be sure, there are examples of lazy and uninspired artists who rely on formula, and formula alone. The distinction should be made between those who use formula, and those who rely solely on formula.
In the end, both lazy critics and lazy artists are at fault. The concept of ‘formula’ is not at fault.