The addiction to constant phone use is definitely a negative, but I haven't found daydreaming to be a positive. Before smart phones in particular I was a super daydreamer. I think for many people like myself, it opens and exercises the pathway to ruminative, intrusive, and anxious thoughts. There is nothing necessary in daydreaming for me, even for creativity. Just being involved in a domain of activity produces the epiphanies, whether I'm day dreaming about them or not. What has worked for me to "cure" boredom is to not cure it at all. To do nothing but sit. To be okay with being bored. Observe the boredom and think "oh isn't that interesting that you're bored." And suddenly before you know it I'm enthralled with what is going on out of the window or I'm washing the dishes before I even really think about it.