As a long-time meditator, I had to weigh in on this one...
First off, I think there are many different types of meditation, and some do involve concentration, at least at first, which might be described as trying to get down to 'one' thought - i.e. focusing on a mantra, visualization, etc.
But ultimately, I think of meditation as helping us get to levels of awareness that are beneath thought, and by doing so, we can open up new ways of seeing ourselves and situations. We can tap into intuition and other kinds of 'knowing'. And that then may be reflected in the thoughts we have, which is why so many creative problem-solvers are drawn to it I think (in addition to the spiritual component.)