Oblivions system was way easier than morrowind ,it presented no challange at any point in the game, besides that it crushed any need for exploration and leveling..
Okay, I wouldn't normally defend Oblivion, the system
was flawed, and it did make leveling obsolete.
Still, there was a difficulty slider. Using it was annoying, because your enemies ended up having [censored] amounts of hit points, but it did make the game somewhat challenging. And also, you should consider that the level of challenge depended hugely on what kind of skills you had trained. With my Restoration + acrobatics + athletics + marksman - character, at a difficulty of 75 percent, I was getting my ass handed to me.
Leveling up was never my motivation for dungeon-diving anyway - I just do that out of curiosity and some vague hope of loot.
And glorifying Morrowind is all good, but really the main difference that I found irritating between the two was that in Morrowind you
would sometimes find places that were simply too tough for you, and you'd run away, whereas in Oblivion you could take on pretty much anything at any level, which broke the immersion.
comparing the actual challenges of the fights seems silly to me - Morrowind combat system was monotonous and very easily exploitable, the fights in Oblivion were more engaging and fun, and could me made more or less challenging with a little slide bar in a menu...