Yes, 2016 should have one more second than 2015. The International Earth Rotation and Reference Systems Service monitors the Coordinated Universal Time and the angle of Earth's rotation in space, or UT1. In order to keep the time consistently accurate, the IERRS inserts leap seconds or removes them from UTC to keep it within .9 seconds of the International Atomic Time. This provides a more precise measurement of the year according to the Earth's rotation around the Sun.
The calendar is not precise enough, and just adding a leap year every four years will not allow the calendar to catch up with the sun's rotation. By adding a second to the year we can help the calendar stay in sync with the sun, which is important for scientists.
No, I disagree with the statement that 2016 should be one second longer than 2015. There is no scientific or other proven reason why 2016 should be one second longer than 2015. The fact that another year is passing does not mean it is necessarily one second longer than the last.
Although I can't really think of any huge impact one year being a second longer than the previous would have, I think each year should be identical in length, except for leap years. There is no reason for one year to have an additional second. It would be best if they all have the exact amount of time.