A limit on an officer's term allows different people to have the opportunity to participate in the local chapters. It also limits the consistency for the chapter. There are too many pros and cons to discuss here, but here are a few things we might want to consider.
With any new position, it takes awhile to become familiar with how things work, what works well, what doesn't, etc. Consistency over several years is important to improving and growing a chapter. You also need to have new involvement, fresh ideas, and energy to accomplish this. Following this thought, perhaps the best combination includes both experienced and new blood.
Asking people for a two-year commitment is a lot to ask, however if someone is willing and would like to commit to a second term, they should be considered for a second term and go through the nomination and election process. The membership will decide if the person is appropriate for the chapter.
Thanks and Happy Coding