I don't think being practical acts as a hindrance to one's imagination. It's critical to actually accomplishing creative ideas. Each skill just needs to be engaged when they're most useful. If you're trying to be creative, then you should be actively trying to pause thinking practically. Then, once you think you've "got something", start looking at the idea practically to see if it's even possible. Repeat until you have a creative solution that might just work. Being imaginative let's you fly, being practical helps you land.