I don’t think the Jungle Bird is a fair example. You could argue that the classic Jungle Bird is actually Giuseppe Gonzalez’s version. He took a cocktail no one remembered or cared about, made it his own and that’s the drink that became popular.
Of course, drinks evolve – just compare a standard Manhattan with the recipes in Johnson, 1887 ‘Thomas’ or Schmidt. That’s not really the point. We’ve been drinking a bourbon-based Boulevardier at the very least since Ted Haigh reintroduced it in his book – I would expect bartenders to make any change to the formula with a word of warning.
What I’d be interested in finding out is whether this change has been bartender or consumer-driven.