I would like the answer to be "release the server for free", but I understand the reality is more nuanced.
Server-side code might have proprietary components or code reused for other games, or a whole lot of complications which are difficult to extricate from a "free" release, and the company might just not want the bother. Releasing something always comes with expectations, just look at how much grief authors of free and open source code sometimes get from entitled users!
But yeah, I would love for game companies to release their servers once the commercial shelf life of a game has ended.
I think it's unrealistic to always expect this, though.
Server-side code might have proprietary components or code reused for other games, or a whole lot of complications which are difficult to extricate from a "free" release, and the company might just not want the bother. Releasing something always comes with expectations, just look at how much grief authors of free and open source code sometimes get from entitled users!
But yeah, I would love for game companies to release their servers once the commercial shelf life of a game has ended.
I think it's unrealistic to always expect this, though.