Like other users have said here, It makes no difference if they choose to join or not, and it may even weaken NATO's unity even further if they do join. Both Finland and Sweden is already working in tandem with NATO and US long before, this would only make their relationship official.
NATO doesn't even have the gal to even send peacekeepers in Ukraine, to make Russian troops back off, despite having every justification and "international law" backing them on this. Instead, they chose to stay behind Ukraine, sending weapons and intel only. It really just shows NATO is for, a client list for US weapons and a tool to influence or drag its members around to do their bidding.
If those countries want to lose their sovereignty on national defense and foreign policy, go ahead. What a waste of potential to gain more for your country by binding yourself to an one-sided alliance.