I did hear this argument before, and it's true. If you manage to find the old Daggerfall forum archives, there are plenty of people talking about this exact thing.
However, not all 'complexity' of a game contributes something positive to its gameplay.
On complexity
If we are going to be honest, there is a lot of crap in Morrowind that no one will ever use (unless a mod makes it useful). Who the hell uses 'Hand to Hand' for anything other than challenging playthroughs? Does anyone use 'Sneak' for anything at all? Is 'Conjuration' ever useful, aside from providing you with a temporary companion or a nice, weightless weapon (that can just as well be summoned with a cheap scroll)? 'Medium Armor'? How many useless pieces of junk in the form of weapons, armor, potions, ingredients and spells are there? Luckily, this can be easily fixed with a fairly lightweight mod.
Daggerfall suffers from this as well, where you have several skills that you can invest precious points in (the language skills) that do no more than provide you with a chance that a certain race of enemies might be passive. How 'useful' is that? Who cares about 'Swimming'? Does anyone at all enjoy the savescumming encouraging system of healing that was present in this game, or the skill that helps you do a better job of healing when you rest?
The bright side of Morrowind
What then makes Morrowind better? The combat system for one, that is so often hated by everyone. It takes into consideration a million little things that don't even matter in Skyrim. Do you have full fatigue? Are you lucky or agile? How much armor are you wearing? How heavy is it? How tired is your enemy? What kind of a weapon are you using? How quickly are you attacking? Do you have a shield, and if so, how heavy is it? Where is the enemy located in relation to your shield? Is your weapon in good condition? The only thing that matters in Skyrim is that you mash LMB, remember to pause to instantly heal and occasionally use RMB to deflect an attack, no matter how powerful. In Morrowind, if your enemy is strong enough to break through your piece of shit shield, they will be glad to do so. Not to mention how pointless fatigue is in Skyrim for anything other than charged attacks and shield blocking - and the health regenerates automatically. This should be a huge red flag for anyone.
How about the quest system? Some guy in Seyda Neen sends you off to Balmora, gives you some papers and crappy instructions on how to deliver them, and politely kicks your ass out the door. Do you have a compass pointing towards Balmora? Is there a big shiny arrow above the house of the guy that you are supposed to deliver these papers to? Hell no. If you want, you can get a ride on the silt strider. If you don't have the money - tough shit bucko. Skyrim holds your hand the whole way through every stupid, generic, pointless draugr killing quest.
Wanna sell something in Morrowind? Haggle with the merchant, try to butter him up so he will give you a better price, and make sure the goods you are selling are in good condition. In Skyrim, you get an XYZ amount - and that is all there is to it. Want to get someone to tell you something they are hiding from you in Morrowind? Intimidate them, bribe them or sweet talk your way to information. Does the speech skill offer any special dialogue in Skyrim? Can you affect the disposition of NPCs so that they start hating or loving you? Can you make them fear you? No, but you sure as shit can invest a perk into getting 10% better prices. What a deal.
And lets talk about the story. In Morrowind, you are a part of an ancient conflict in some backwater province of a decaying Empire, trying to calm down everyone so that they can focus on the real threat - a mad living God that stole power from another God. Lotsa living Gods are involved here. Tell me, why does the Sixth House set up bases in caves near the coast? So that they can infect people in nearby cities with nightmares. Why would they want to do this? Because their leader, the mad God, created a disease that turns them into mad monsters, willing to questionlessly do his bidding. What is Dagoth Ur's endgame? He wishes to drive out a foreign invader and restore and ancient Dunmer empire. Why does Alduin attack Helgen? Dunno, lol. I can't even remember why he did what he did.