Should we retire #17?

Marty Noble at Mets.com writes about the most influential Mets players and the numbers that should be retired:

Hernandez was the most critical figure in the Mets' run of success from 1984 through 1989 -- all first or second-place finishes. He changed the team's sense of self in 1983 when the Mets acquired him from the Cardinals and led the National League in MVP points -- without winning the award -- from '84 through '88.

Each generation of champion Mets teams had its leader -- Seaver for the '69 and '73 Mets, Hernandez for the '86 and '88 Mets and Piazza for the 2000 team.

So why not Hernandez or Piazza for retired numbers?