Doom gets ported because it has extremely efficient code written in low-level language so it's easy to port and runs well even on potatoes.

There literally no point to put in all the work to port Winamp to a completely different sound system and to have none of its plugins work, when there are Linux clones that already work, have their own plugin ecosystem, and can use Winamp skins.

If they use a FOSS license there's a non-zero chance someone will bother in spite of all that, just for fun. But if it's not FOSS that takes all the fun out of it.