I don't think so. I have worked on problems where most of the team had their head in the clouds, dreaming up wild solutions, and then we end up going with a team member's solution who suggests something very easy, requiring almost no technical skill, that should have been obvious, but all of us missed.
Practical is good. What will actually kill your creativity is self-doubt. Stop doubting yourself and be happy with the way you are.
I think that maybe it's the difference between simply "imaginative" and "creative" - creative implies that you're involved in the act of creation. Things can't be created in impossible contexts, so part of being creative is understanding and accounting for the constraints you're working under.
And I'd even say that the issue is not that practicality kills creativity, it's that creativity is hindered if a person doesn't fully understand the context in which they're creating.
Practical is good. What will actually kill your creativity is self-doubt. Stop doubting yourself and be happy with the way you are.