Morrowind is a great millstone on the Game history because it holds the pure essence of the roleplay: Is like life.
I mean, the beginning is so simple as exciting: you're a prisoner that has been released in a port by order of the king. Congratulations, now you're a free men. Do whatever you want... find out why you have been released (the main quest), or do your own life, get a work, enroll into a guild, explore the world, go and make tourism on elvish cities, read books, master the sword or the magic... there's no limit to you freedom, you're in a HUGE world and you feel free to live in it as you wish... i never got that in a game: all RPGs makes you work in a direction, or gives you some requirements to advance, or you're forced to do several task before blablabla... not on Morrowind. The first month playing i never did a single quest. I pass weeks and weeks travelling, locating cities, chating with people, getting info about the world, the history, races... this is simply unthinkable in other games.
Morrowind is so great that allows you to build your character based on your own mind: i mean, you're going thru the forest and you find a slaves camp. Do you want to release them? Do that. Kill all and get the bounty? go ahead, it's on you... do you want to master the sword... axe... archery? maybe a bit of all? Magic? restoration? destruction? illusion?... you can get ALL, is only a matter of time and money, there's no restriction by races, classes or anything, you can get what you want by working it.
And what RPG allows you to buy a candle or a spoon? Just this, because sometimes you're tired of killing all living thing on a Dungeon, so usually you just turn off the game, but Morrowind allows you to find a place and build there a home where you can display your weapons, bring food to the kitchen... and much more.
Of course the graphics are very good and all the tech aspects are excellent, is full of dungeons, quest and classic RPG elements... but there's many things to do in such a BIG world (with many different environments) that the life of the game is almost unlimited, and best of all: you are so free and the world is son complete that it's easy to get involved and think that you're the warrior on the screen looking in all the stores od the realm for the left gauntlet that will fit on your black ebony armor... Thanks to Morrowind, many of us can forget their real life for a few hours going to the next town to find... whatever you're looking for.