As a writer, it is definitely a positive to have an overactive imagination.
I go on a walk, look at a house very different from my own and immediately make up complex stories about events that have happened inside.
At a restaurant, I see a mother and son eating together and their invented conversation flows easily from my mind.
Not to mention that I can write a 50,000+ word novel based solely on a dream. (Which reminds me, I need to remember to write down the slightly bizarre, yet fully fledged plot from this morning's dream.)
On the other hand, in my non-writing life, my overactive imagination has its downside.
When I feel slightly unwell, experience slight abdominal discomfort for example, the gray matter jumps from appendicitis to cancer, and then to death!
If my husband is 20 minutes late bicycling home during a snowstorm, the image I see rapidly becomes a car/bicycle crash, which leads to inevitable death!
It is actually a little disturbing just how quickly my brain heads to death. But that's only because I have an overactive imagination, or so I tell myself.
I guess the answer to the title question is — yes.