I'd say we're half evolved. We have this facility and don't know how to properly control it. It's a byproduct of some other facility (the ability to communicate).
I think we're always "half evolved". Our minds and bodies are an amalgam of "good enough" traits for overcoming yesteryear's evolutionary challenges, not entirely suited for today's challenges.
I don't see any link between (1) communication and (2) my mind wandering away from my immediate surroundings and settling on an outstanding problem I have. My mind could (and occasionally does) wander over a million other things in my brain (e.g. past memories, imagining the future, or the feel of my clothes on my body) but predominantly focuses on outstanding problems, so I tend to think this is a highly purposeful adaptation.
It may indeed serve a useful purpose to have a wandering mind, but as the article points out "the hallmarks of many forms of mental illness is a preoccupation with one's own thoughts", i.e. perhaps the issue is the extent to which one's mind wanders. Not all minds wander equally.
Personally, my wandering mind has been my greatest strength and my greatest weakness (anxiety, worry, jumping to conclusions, all or nothing thinking, etc.). I spend too much time in my head and not enough time grounding myself in reality to the point where there is serious disconnect in my awareness and mindfulness of situations (which has caused all kinds of serious grief in my life). Meditation has been recommended to me numerous times, and based on this article it looks like it's something I want to explore.
The ability to communicate as we humans do requires the ability to abstract, be removed from reality and ponder over it, so you can articulate your problems to others. The stories in your head are just that, except you haven't verbalized them yet.