As the person who brought this to the point were the members can actually have a say in the matter, I suppose I should say something on the upcoming vote too.
First, term limits are a normal, widely used, safeguard against incumbents overstaying. They do come at the expense of sometimes forcing people to step down that you in principle would like to stay on, but that is the nature of the beast: such a restriction has to apply evenly to all. As Frederik and others have pointed out, there is essentially nothing in OSM that requires a board position for you to help with the project and there are more than enough things former board members can help with if they are so inclined. Matter of fact making a board position a prerequisite for helping with OSM is IMHO a reason for immediate disqualification, as any notion of entitlement to such a seat.
As Randy Meech has pointed out many times, you currently only need a small number of votes to get a seat. Any board member worth her/his salt will easily have a power base large enough that will guarantee constant re-election for as long as they please. Maybe some day in the future the OSMF membership will be so numerous that the danger no longer exists, however that is a long way away.
Some concerns have been raised that the OSMF might run out of potential board members with such limits. As we saw at the last elections, there is no shortage of capable candidates, and if you are really concerned, please accept the 2nd special resolution, which in practical terms completely removes any such issue.
Nobody is claiming that term limits will solve all problems with the OSMF board on the structural side. A number of other items that have been touched on that need addressing too, for example actually defining terms for board members. Please do not let yourself be confused, these topics, while important, have nothing to do with issues that the proposed changes are designed to address and are no replacement for them.
Kate has claimed that the just past election has provided “enough changeover” that the board should simply be allowed to carry on as is. To believe that needs a gigantic leap of faith, two relatively short serving reformers have simply been replaced by two even fresher reformers.
The balance of power in the board has not changed at all.
In the interest of the OSM project and the OSMF, please vote yes on all three resolutions.