Why was this decision even made? Am i just out of luck because i dont have access to something anymore because of reasons out of my control?

There has to be a way for me to link my remove and relink because its unfair for bungie to shrug their shoulders and go "Oh well" for something that can happen to anyone.

There isn't, Bungie in doing the above change also made a point of closing the workarounds that players were using to move away from accounts they couldn't access. Their reasoning for it is 'Our goal is to protect the integrity of our players' accounts, simplify certain security systems, prevent fraud, and limit activities that go against our Terms of Service.'. Personally I think they got tired of people not maintaining account access, were just freely linking accounts knowing there were workarounds, were account sharing/getting recoveries done through players linking another platform account to do it, and some used the workarounds to get around them having deleted linked accounts. Yes people can get into a situation of them losing access to an account but as far as Bungie are concerned the player should have enough recovery methods/evidence (ie writing down serial numbers, keeping email receipts, properly setting up security questions) with their platforms so that it isn't a problem to recover the accounts. The system now gives zero leeway to players because of the actions of other players.