Blue-sky thinking conjures up open-minded and creative thinking. Thinking that will ideally result in new out-of-the-box solutions to business problems. When my former boss, an American, used it this was his intended meaning.
But according to Wiktionary, there’s an alternative meaning; Thinking that is not grounded or in touch in the realities of the present. I think my lovely pragmatic Dutch colleagues understood this meaning.
So a boss might be encouraging his team to be creative, to imagine wild solutions, but a pragmatic or cynical team might be hearing “let’s waste some time thinking of solutions that can never realistically be used” and that’s a demoralising thought. Maybe it’s better to include some of the pragmatic limits in your briefing. Perhaps offering to fund a pilot of the best idea would give people the freedom to think creatively and reassure the pragmatists in the team.
Read the room before you use this phrase.