Your definition of creativity is flawed. Imagining something is a small part of the process. Developing the skill and technique to express that imagination is the most important part.
Sorry, but most ideas aren't great. It's the painful process of refinement, hard work, and iteration that results in something great.
Many. And I love it when those people code something up with Scratch, Matlab, or even Excel. Even though I personally would dislike the aesthetics of the result, I’m much happier to see other people enjoying computers the same way I enjoy them (i.e., by using them to solve interesting problems) than if I insisted everyone do so using my preferred “real” programming languages.
Regardless of the tool used?