As a fan I would have loved to see him continue and it is always sad when a rider of his caliber retires. So many memories of watching him race. At least it is not a "what if?" situation. He won it all and he had 15 seasons as a pro. Still being one of the best riders in the peloton when he retired. I like the bittersweet ending from a fans perspective. Sad to see him go but he ended on a good note.Of course that needs to be taken into account too. But at a purely sporting perspective, it was sad to see him bow out so early.
Five years before Valverde who is two years older than him (I'm not saying he should have continued seven more years, though).
Valverde is just Valverde. He is great and incredible what he can do still, but he would probably have retired earlier if it wasnt for his loyalty to the team. There is also factors like his serious injury in 2017. He wanted/needed to recover, came back and managed to win the WC, so of course he had to race another year with the jersey in 2019.
Then if I am just speculating he might have wanted to retire after 2020, if the pandemic didnt happen. This year he might have thought about it too but Movistar in Movistar-fashion Movistared come the end of the season. They still need him more as a rider than anything else, if he still could press on for another year at a high level. Making good results and scoring points for the team.