To all the people who say Morrowind's combat system is horrible...
You're wrong.
Morrowind was based on RPG mechanics. You can tell your character to swing their weapon, but that doesn't mean you'll actually HIT anything. Anybody who has played pen and paper games understands and accepts this. Unless you're actually skilled with a weapon you will not land hits except by pure chance. Combat was based on your character's performance, on their weapon skill, on their fatigue level. In Oblivion and Skyrim, that is lost completely. You swing, you hit, you block, it's all YOU. Not your character. There is no sense of progression from prisoner to hero because the only thing that changes along that timeline is the color of your weapon and how much damage it does. In Morrowind you cannot start a character who has no weapon skills and then expect to fight everything and win with fancy footwork. Even a lousy mudcrab will kick your butt if your Killing Stuff skills are only 15, just like any other non-militant villager.
And then there's all the ways that Morrowind does not hold your hand.
* Your journal is complex, huge, descriptive. A long running game will easily push your journal past 100 pages of information, and you will have to actually USE it to keep track of what your objectives are. When something you were told three months ago suddenly becomes relevant, and you're leafing through your journal, you see all that you've accomplished and there is a strong sense of "This is my life here in Vvardenfel, this is what I have done".
* Weapons and armor wear out. This is good. It makes a skill useful, requires strategic planning (Do I keep going deeper into the cave or do I retreat and maintain my gear?), and is immersive.
* Fast travel is "in game" and actually MAKES SENSE. Want to go from Balmora to Tel Mora? Well, the mage's guild can teleport you, but if you really distrust the guild you could take a strider to Vivec and then a boat. And then there's the propylon indices, mark-and-recall, two different kinds of one-way teleportation, scrolls of windwalking... Getting where you going required five seconds of thinking to look at the most efficient way of doing it. You can't even really opt out of fast travel now in Skyrim because there's only one form of "in game" fast traveling to Morrowind's half a dozen, and it's horribly limited in its destinations.
* Health and magicka do not regenerate. Want to be healed or refreshed mid way through the dungeon? I hope you brought potions then. You DID plan ahead, right?
Etc.
Basically Morrowind offers more challenge, more immersion, and more options than TES4 or TES5. And that's why many still love it. Sure the graphics are pretty bad now unless you pimp the heck out of the game with mods, and sure it's not as polished as later games, but it has a stronger self identity and is ultimately a more rewarding experience when you triumph.