Look, I enjoyed Skyrim, but I miss the days when Bethesda made RPGs
I wouldn’t say Morrowind is deeper than Skyrim mechanically, but it is more complex
You’re gonna have to back that claim up cuz it’s pretty weak
Immediately spell crafting and the entire magic system come to mind. Skyrim’s system is absolutely puddle shallow by comparison, and that’s before we get into all the other skills and abilities that got watered down, merged, or removed
Morrowind has significantly more mechanic depth than Skyrim does in just about every mechanic the 2 share
Armorer (smithing), alchemy, athletics (gone), block, enchanting, unarmored (alteration perk), weapon, and armor skills are the same or better in their Skyrim versions.
Enchanting and magic were far more powerful in Morrowind, but also game breaking. They aren’t game breaking in Skyrim, but magic is limited. Having actual mana regeneration is huge though. Again random chance to fail isn’t a great mechanic, higher level magic requiring absurd mana when low skilled does a better job of creating a power curve. Leveling magic in Skyrim actually requires it to affect things, which is more interesting than making a 1 mana spell.
Combining speech craft and mercantile was also a good change. The disposition system was super basic, just bribe anyone that didn’t like you and taunt anyone you want to kill. The random intimidate\admire system works better here as you can’t just keep trying with bribes\taunts to get what you want. Taunting people to death isn’t that deep.
Skyrim arguably offers better combat depth as it’s far easier to utilize combinations of magic, powers, shouts, melee and ranged combat. Combat is hardly deep in either game, there’s more options in Morrowind, but it’s more about what color you want the magic than anything deeper than Skyrim.