I think time traveling to the future would be dangerous. They say that time travel to the past would be the most dangerous, because of causality (you effect something small in the past and it botches up your "present" hence why Adolf Hitler gets assassination-immunity in most time travel stories). I think future time travel could potentially be more dangerous, at least on an individual level.
Frankly, I don't want to know my future. If I knew my "future" (present) in the past, I might have let myself die before my time. In fact, I once wrote a really bad short story spurred by an idea I had that "maybe I was supposed to die back in the past, and I'm temporally-displaced and that's why I'm so miserable now." I've gotten a *bit* better since then, but only by a bit.
Seriously, if I were to travel to the future and look my future-self up, I might find my future-self as an old woman, homeless and eating discarded Taco Bell out of a dumpster. If that is my fate, I do not want to know it. I would lose all hope for the present.
Likewise, if I were to travel to the future and find out that I've become the next grand fantasy novelist, or that my art has changed the art world or something cool like that, where my vision is seen and my voice is heard - all my wildest dreams... I might come back to my present with a loss of ambition. If I'm going to achive these great things anyway, why *work* so hard, why *try* so hard? That would lead to apathy, and to boredom, which would be just as dibilitiating to me as a loss of hope.
Also, imagine, if you will, traveling to the future so far that you wouldn't run into your future self, just to see what the world and society are like. What if you came to a future where everything's been destroyed in a firey cataclysm?
Or, perhaps even worse, the world is a shining utopia where everyone gets along and everything is just utterly happy, BUT this world is one that has no room for "people like you." Say, you're a Republican and this perfect world has abolished the Republican party, or you're religious in some fashion and this world is the shining athiest utopia that so many science fiction writers have thought will eventually happen in the future, or, conversely, perhaps you are an athiest and this world is, as strange as it might be, an explicitly religious utopia where people have come to agreement or some kind of "right way." Or, to give a Futurama reference, maybe you like Star Trek and in this world a thousand years in the future has come to see Star Trek fandom as dangerous and has banned all things Trek with extreme predjudice....
Long story short, you come upon a perfect, world, but find out that you are and always were WRONG and, what's more, this world has had to *rid itself of people like you* in order to become right. Now, how would that make you feel? Would you go back to your time and commit suicide for the sake of perserving the future? Perhaps you would gather others like you and tell them of this, encouraging them to "die and get out of the way" for the sake of your decscendants' happiness?
And all of these things could drastically change the futurescape from what it was once going to be.
Unless of course, your time travel into the future is as such as it does not allow you to return to the past or "your time." One-way trip. I think causality is minimized if not elimiated if it's only a one-way trip. After all, we are *all* traveling into the future in momentary increments and it's a one-way trip.
Also, I see time travel, particularly in regards to the future and changing stuff and being able to come back as something that would create multitudes of different offshoot universes - either that, or we'd all be traveling, messing up things so much that, much like the rest of nature, we humans would ruin things. I could see we humans, should we gain TARDS-es or Flux Capacitors just turning Space-Time into soup. Gray soup.