Honestly, I feel like singing should’ve been in base game. It ties into so many aspects from other packs, like the acting career in Get Famous for example, and usually they seem to just replace anything that would logically use singing with guitar. Similarity, the base game entertainer career could’ve also just used singing for promotion requirements too.
And if we ever get a pack with bands, logically singing should also be a pretty big component. It just seems to tie into so many other packs and is only vaguely related to City Living.