That's pretty fun too (Rudy Rucker fan reporting for duty) but the complete lack of restriction can sometimes limit the creativity too, since creativity is often about solutions to problems, and for most problems to exist, there need to be constraints.

There's a good deal to be said for realist-ish sci-fi, as long as things are internally consistent, and there are some constraints to help both give interesting structures to the universe and society and to drive the plot forward.