Skating is a big difference here. Larkin's speed will keep him competitive as a top 6 forward well into his 30s. All keeping Bert would have done (assuming he was even willing to re-sign, which all signs point to he wasn't) would have been to make the team not bad enough to get good and not good enough to win anything.
Yzerman should have moved Hronek and Bert last year and went all in on the Bedard tank this season.
Hopefully this offseason he relies more on youth to fill roster spots than signing vets again. There are enough vets with winning experience on the roster as is.