Yes, any job which one would describe as "grueling" falls in the category of jobs that people only do because they're paid. These should always be phased out because it's a net gain for everyone as long as there's UBI.

The jobs that we should be more worried about are the ones you listed such as musical composition and directing. These are jobs that people genuinely enjoy and would enjoy even if they weren't paid. Automating these is always a double-edged sword because while there's a productivity gain, there's also a "meaning of life" loss.

The objective metric of unemployment is the unemployment rate, which is still low. We don't need UBI until that becomes very high.

Edit: Actually it also depends on wages. Due to wage stagnation I guess you could make the case we need UBI already.