The continued existence of an MS-DOS port doesn't detract from versions for current operating systems in the slightest... Vim and Emacs even maintain current ports for MS-DOS and I doubt anyone is going to give them up just because a DOS port exists.
NetHack 4 is a radical shift for the game, and many of its ideas were incorporated into NetHack 3.6 (the upstream project), I think even its developer was placed onto the devteam for upstream NetHack while maintaining the fork simultaneously. It's a cool project, but NetHack 3.x is the conservative one, both in gameplay and in maintaining ports to operating systems of yesteryear (they clearly aren't against removing them, but they support them when there is at least one person to maintain it).
NetHack 4 is a radical shift for the game, and many of its ideas were incorporated into NetHack 3.6 (the upstream project), I think even its developer was placed onto the devteam for upstream NetHack while maintaining the fork simultaneously. It's a cool project, but NetHack 3.x is the conservative one, both in gameplay and in maintaining ports to operating systems of yesteryear (they clearly aren't against removing them, but they support them when there is at least one person to maintain it).