"descend/sink/stoop to someone's level
: to behave as badly as someone who has treated you wrongly
▪ Despite my opponent's personal attacks against me, I refuse to stoop to his level. [=I refuse to behave as badly as he has by attacking him personally]" Merriam Webster Dictionary
.,,.
I think it would always have been a phrase with a pejorative or contemptuous overtone, Steve. Barry was surely talking of, and meaning, the degeneration the song had undergone.

~M~