Depends I guess if you plan to travel outside of the country in which case you need to renew your PR card. Generally not a bad thing to renew a card given never know if you might need to make that unexpected trip abroad plus the citizenship application takes a while anyway.
It is a bit like the argument about keeping an upto date passport and suddenly realising you let it lapsed when you have a family emergency to attend to. For the sake of filling in a few forms and a few dollars for documentation that has a few years validity if were me there is no debate.
Of course if you have no plans to ever travel then there is only one course to take which is to apply for citizenship as soon as qualified then you can get a brand new shiny Canadian passport and ditch the PR card requirement
