While I believe that the player should be remembered and written into legend, perhaps. You can't leave a gaping hole in the game because so-and-so decided not to play anymore.
After you spend 2 months, a year, two years creating something glorious you should be proud! And you should hang around to protect your interest. When you leave you no longer can expect to retain the same position. Why shouldn't someone else have them.
It's ridiculous to think that a major part of the game should be lost because one person has a fit. Once you add to a common idea or group project, you give those ideas to the group. You should always be given credit, but realize too, that work, that idea, that action, no longer belongs to you alone.