I've played it shortly, can't see the appeal.
The appeal is to slap 150 mods on it and expect it to become a good game. Unfortunately, in these 11 years since its release, none of the mods fixed the core issues with the game: lack of world building, lack of world reaction to player actions, lack of player choice, etc.
Modded Skyrim is a glorified open world free-roaming game, and that's it. It's not a sandbox, since you are extremely limited on what you can do that directly affects the game world. It's also not a RPG, since there is nothing the player does related to the story/plot/quests that have any consequence whatsoever; you can kill the fucking emperor and the world does not acknowledge that fact. At all. A larping simulator is probably the best way to describe Skyrim, since everything happens exclusively on the player's imagination.
Some claim Skyrim is all about the exploration, but the reality is that there is nothing to discover. Every cave, every dungeon, every ruin, have nothing in them other than enemies for you to slain and some fat chest at the end with 50 gold coins and a ruby. Discovering "interesting" NPCs is also a fallacy, as there are none. No NPC interacts with the player in any meaningful way. They have no backstories, no dialogue, no purpose on the game world other than give you quests, and zero interaction with the player regarding the events that unfold as you progress on the extremely linear story of the game and its side quests. The so called "lore" present in Skyrim only exists in books spread throughout the game, and most of those were copied from Morrowind and directly contradict the events on Skyrim itself, so talk about shooting yourself in the foot.
The game systems are also broken and not fun. You can become proficient at every skill by grinding alone, and only by grinding. But to what end? The entire game revolves around killing enemies and leveling up. There is next to no player skill involved in this game, so it's not like you become more proficient at the game either. The speech tree is useless, as there are no NPCs to interact with to make use of your speech abilities.