History is full of examples of visionaries coming up with ideas that have inspired and fueled others--in some cases whole industries have been founded on these ideas. For instance, Doug Engelbart gave the "Mother of All Demos" in 1968 [1]. It was a proof of concept, but the ideas he talked about were implemented by other companies--who profited from it.
It is unfortunate that we live in a world where ideas hold such little monetary value, but they're most certainly not worthless.
Bell Labs was responsible for much of the underlying technology, and these applications had been foreseen. But they were undoubtedly deluded about their ability to deliver those applications.
Doing something well means you already imagined doing something well first.
Or, in other words, "imagining doing something well" is necessary, but not sufficient to actually do something well.
Coming up with an idea for something, and then sharing this idea with other people in an open manner, can plant the seed that germinates the execution for that idea.
To me, that's part of the reason why thought pieces are valuable to me. Also, unconventional tracks at academic conferences, like provocations at DIS 2020 [1] (which I cite here since it's on my mind because I'm personally applying to it right now).
I mean, you're not wrong, but at the same time whether you call it "imagining" or "coming up with ideas", if done well the results of said process are valuable.
One should also consider that good ideas usually come out of having a lot of domain knowledge in a particular area. And that requires effort and work ("execution" but in the past).
This was also often the conclusion found during the Dark Ages. ;D