Fun is subjective. Fun is faciliated by mechanics. Fun is not faciliated by traits that make up RPG elements. When you complain that a given task in an MMORPG is boring or tedious, then you are not complaining about the task at hand but how it has been implemented.
As I replied and you failed to consider: it's about having the mechanics in place to faciliate solutions to problems that might make things such as bag space a tedious mechanic in an MMORPG. Such as warehouses or banks where you can safekeep loot and items.
Yes, humans will always pick the path of least resistance, we are by definition lazy creatures. It has everything to do with being lazy. If the mechanics are not in place to involve the player and make him think about in-game repurcussions/consequences and solve them creatively (other than tossing items away), then the tedium begins. Why? Because there is no engaging or creating solution to the problem. It's just present. That is true tedium. Tedious things like weight limitation can incentivise immersion and meaningful choices if mechanics are in place to support player choice on how to approach the problem.
Do you understand this logic?
There is no way in a million years that you will ever find activities everyone find enjoyable or engaging. Anything and everything can be tedious. Or annoying. It isn't so by nature, but because on its own it holds no meaning.
Killing a specific number of a certain mobs is tedious, why is it so? Because it is an arbitrary limitation with no failure state (if you disregard the fact that failing to meet the requirement is a failure state) or solution which gates your progression behind time.
How can it be made more immersive or less arbitrary? You can introduce time limitations. An NPC could require a set amount of cloth lootable from humanoid corpses in a nearby location before 20 minutes has passed. Reason? Another NPC would not receive treatment on time. In Darnassus, the starting zone for night elves, one of the first dozen quests you did actually had this system in place. You had to carry an item to another NPC within the time limit or your quest failed. Unfortunately, such quests would be dependant on mob density (it would be tedious/annoying if you were lower level and got constantly killed while trying to complete the quest) or pure RNG (the cloth never dropped).
People would always find something to bitch and moan about in WoW. The game is old, they just want to consume content efficiently, as the idea of exploring is long dead in WoW. That makes it very hard to design meaningful choices and quests in relation to RPG elements. Q.Q this, Q.Q that. The forums are littered with such an entitled attitude. The terms tedious, annoying and nuisance are one of my pet peeves in WoW. They use it as an excuse for removing factors and traits that are RPG related just to make things more convenient, instead of setting up mechanics or creative solutions to the tedium it represents.
Players quite literally need to be forced to immerse themselves or have fun. There are exceptions to this, but usually the exceptions are based on sandbox elements, where construction or decision is left in the player's hands. Minecraft, etc. Aka: fun lies in choice. For a common thing to be fun it needs to offer meaningful choice. For weight limitations to be an engaging factor in immersing the player, the player needs to be able to choose how to resolve the problem in more than one way.