Some MPs are made for this job and maybe can contribute great things to a government. For others, maybe this job isn't made for them, and they realize that after some years.
Through this system, it seems so random. You may end up losing some of those who have really good potential and end up having all the people who were in safe seats winning—those who won by a greater margin—but there could be others who won and who are equally deserving. Explain that to me, because at the end of the day, I think citizens do want to see good potential in their government, as well as proportionality.