I like that you raise the question, because people need to wonder more about usefulness. Not the robots: us.
If we don't question what humans are going to contribute to our place (Earth, life, etc), what difference does it make if we build robots to be our replacements to consume the planet or if we do it ourselves?
The ethical problem is that humans serve authority, rather than our resources.
Robots are the wet dream of aristocrats because they can (supposedly) be programmed to obey (slavery).
People have to be coerced by expensive marketing techniques and bribes to act against their own interests.
Dancing robots are the least of our worries. It's the dancing people who are being programmed.
Call it whatever you want (choreography, consumerism, culture, philosophy, democracy, morality, religion), but it's all in the marketing, and it's ALL marketing.