Thankfully, our WM-to-be has made it a point to state that any officers who wish to take office need to be there for not just stated meetings, but degrees, floor school, etc as well. In fact, our SW-to-be, opted to step down this next year because his business occupied too much of his time and he felt not able to commit enough to his position. Hard decision to make, but it is good to see men making decisions for the lodge and not themselves.
Things will come up from time to time and life does happen, but like you said, it is easy to pick out the brothers who are dedicated to attending and those who are not. I too feel that if you accept an officer position, you are committing your time to always be there during your term. I'd like to see other brothers always attend, but that is another discussion altogether, hah.