That is a question worth considering. As you just said about the current system, less than 3% of the population belongs to a political party. Closed lists are not a perfect solution, but they are a way of increasing stability. Moreover, if a candidate withdraws during their mandate, it is easier to call upon new elected officials.
I do not have the figures to back up this statement, but I think a proportional system—or a system with more proportional aspects—would increase the importance of more political parties, which in turn would increase public trust. Over time, one might expect confidence in public parties to increase, which would encourage more people to join political parties.