They were among the first open-ended games that I remember, where you could totally ignored the story line and just "be a pirate", if you wanted to. It had role-playing, adventuring, action, and greatest of all, piracy!
They were just plain fun!
Today I came across This press release from Firaxis, Sid Meier's game company, detailing that they are working on a Pirates! remake!
Now I just need to hear that LucasArts is doing another Monkey Island game, and that Sierra's doing another Quest For Glory game, and I'll be totally content. ;-)
 This last is, unfortunately, almost impossible at this point. A few years ago, Sierra killed the division that had been responsible for the truly great old Sierra adventure games.