a major characteristic that makes it a perennial draw is imo that its so generic and mid. plus the technical side that it Just Works better than oblivion.

in a an actually good game completely altering core systems and questlines would actually risk you losing something---incidentally FNV has a lot less of this, and expansion-style is the main way stuff got added, since the original stuff is good. but with Skyrim? there's overhauls for every questline and mechanic, because the base was so barebones. ive played like 6 different experiences doing the Magic School in Skyrim with different mechanics & progressions.

Hmm... this is actually kind of difficult for me to answer because I bounced really hard off of vanilla Skyrim when I tried to play it. I have a lot of negative things to say about the base game, and the version of the game I like to play is similar but still very different in almost all systems (ie I am a Morrowloot fan)

I guess what draws people to Skyrim is

• Skyrim's visuals are still pretty enough looking (especially the engine update re-releases) that the average graphics snob isn't going to be immediately turned away like they would for Morrowind and Oblivion
• Similarly the combat is approachable and responsive enough to not turn action gameplay snobs away immediately, at least not until the 5000 HP draugr deathlords start spawning
• The explore, combat and loot loop is admittedly pretty well done. Picking up a story side quest and stumbling upon a dungeon to explore on your way there is a satisfying gameplay segment. So is finishing off a chunk of gameplay and hauling your stuff to the market and/or your house
• There is (just barely) enough 'character types' to justify multiple playthroughs dedicated to different gameplay builds (ie evil Dark Brotherhood daedric quest character, College of Winterhold character, Companions werewolf build, Dawnguard vampire run, etc)

I used to make mods a lot, but I got severely stuck on blenders texturing tools back in 2011.

I played hundreds of hours in Oblivion in a single playthrough, but I had so many mods - Elsweyr and Valenwood, sailing ships, a de-levelling mod, vast amounts of new enemies and mobs, new quests, tons of new game systems. I waited over a year to by skyrim and fallout iv to give the mod scene time to mature.

I also really, really like the tes backstory. Skyrim and oblivion were,kt nearly as weird and fun as morrowind in that regard, but if you look you can still find some of the weird charm - Camoran's rantings in the Mysterium Xarxes, the painted world, the thieve's guild's relationship with Nocturnal, the backstory of Knights of the Nine if you just ignore the boring crusader armor, the whole shivering isles expansion.