Term limits were given to limit the power of the representatives. This will not give them the extended time to be consumed with their power and be corrupt officials.
Term limits also act as deterrent to those who are running for office whose purpose is not entirely to serve his constituents. In this way, those who are determined to be of service to the public will only be the ones motivated to run for office.
The term limits also give the representative their deadline. It will encourage them to accomplish a lot of things in a limited period of time. He or she will not dally in proposing bills and passing laws because time will come that he will revert back to being a civilian constituent.