With the astrophysicist community talking about solar systems like ours with earth like planets, there is one question: How do we investigate such systems that are light years away? By the time we get any explorer craft back from a round-trip exploration mission, there might not be humans available to analyze the data.
Look, it was just a few years ago where we had no proof whatsoever other solar systems even existed. Now we know these systems seem to exist through out the entire universe. Should we have said at the time, "Why bother, we won't be able to get there and back for thousands or millions of years anway?" This was all done without sending anyone anywhere. If you're waiting for a manned spacecraft or even a unmanned spacecraft to go to the stars and return with data, you have a very long wait.
It's why non-manned missions in our own solar system are conducting research and collecting data and transmitting it back electronically. So much data we'll be studying it for years to come. As technology currently exists, humans could never go or do what our unmanned spacecraft are doing.
Bottom line here, if you're talking about going to the stars it will be done by relying on optical and other types of telescopes and unmanned spacecraft, to visit, study, and research interstellar space outside of our own solar system, for hundreds of years to come.