When I hear the argument about "why would aliens come here? why would some super intelligent interplanetary species be interested in us?" or if I hear about aliens potentially meaning harm, I think about a quote from the protagonist played by Jodie Foster in the movie Contact: "We pose no threat to them. It would be like us going out of our way to destroy a few microbes on an ant hill in Africa."
The antagonist government bureaucrat goes on to say something like "and how bad would we feel about destroying a few microbes on an ant hill in Africa?" -- and that's a good point, something to think about, and it sheds some light on the scientific vs militaristic attitudes we battle on Earth today.
However, using our own advancement as an analog, because that's really all we have, I think if we look at the intelligent humans amongst us, the ones who actually lead scientific fields, the ones who bring us into the future, they are not destructive in their goals, not militaristic -- we can see that science has an interest in studying things like microbes on an ant hill in Africa, even while the general population cares not at all and, quite contrary to wanting it destroyed, science wants it preserved so it can be studied and learned from. Intelligence has no interest in wanton destruction.
If our own civilization is to advance it will be this scientific attitude that advances us, it's what has advanced us, despite the desire of so many to use science for anti-scientific destruction. I've tentatively concluded then, from this optimistic logic, that the most plausible explanation for any possible alien interest in us is just that -- scientific exploration.