Skyrim is a totally different beast because the ingredient effects you know about don’t depend on your Alchemy skill anymore: instead you simply discover the effects by successfully making a potion with them. So there’s a sort of minigame of trying different ingredients together to discover what kind of effects they give to potions, which in my opinion is neat because it matches up with how you might do this in reality.

I think the developers didn’t like the “surprise” extra potion effects you could get in Morrowind, so they changed it in oblivion.