Outside the entrance to the king's palace.
Helen: "Ulfar! At last!".
Ulfar the Mighty: (Slightly out of breath) "Sorry I'm late everyone, I had a bit of trouble on the way in".
Samantha: "Ulfar, is there a small squirrel chewing on your arm?"
Ulfar the Mighty: "What? Oh, this. No, it's the latest in adventuring fashion. It's, uh... I... Oh who am I kidding. Excuse me ladies, I just need to run in a straight line for four hundred yards to get rid of it".
Comes running back, with five small animals all hanging from various limbs and appendages, all of them gnawing away in a furious and yet fruitless fashion.
Ulfar the Mighty: "Be right back".
Four hours later...
Helen: "Where the devil has Ulfar got to? We're supposed to be getting a quest from the king and the royal party is almost over."
A mound of forty or so writhing animals from around the countryside shuffles into the room, shifts around a bit and mumbles something unintelligible before collapsing in a heap on the floor.
In many MMOs mobs that are far below your character's level will still aggro. Admittedly it may be that the games will implement an aggro range, such that higher level mobs will aggro when you step foot on the same continent as them, and the vastly lower level mobs will require you to get fairly close to them before you get their attention, but invariably you will get close enough, and you will get their attention. And that's about all you'll get. They don't do enough damage to threaten your character, although it's just enough that if you're suddenly jumped by a suitably tough mob you will be disadvantaged. They don't give any XP because they're just too low in level, or if they do give XP it will be of any value you like as long as it falls between one and three. They don't drop any loot worth writing home about, in fact half the time it's just junk that will fill precious bag space, although just for added aggravation they will all drop the animal part you needed for that quest fifteen levels ago which you had to spend four hours grinding away for. Some of them will drop two, even if that part in question is, say, a nose...
The fact that these mobs can hit you at all is a total insult to your heroicalness. You're standing around in your armour of wonderment with its plus five bonus to Glinting Sexily in Sunlight, and suddenly a guinea pig sneak attacks you and starts doing annoying but negligible damage. This is a standard guinea pig mind you, not one of those dire, aged guinea pigs of yore, that would roam the frozen wastes of Niflheim and lay waste to entire villages with their mournful squeals, and who could only be appeased with a giant peanut from Yggdrasil. So there it is, this standard run of the mill guinea pig doing damage to you with its species' centuries-evolved ability to find weak spots in chain mail, and you have two options: fight or running away, because the feisty little fellow certainly isn't going anywhere, he's made the catch of his life and he's going to take you down, one hit point per hour until he is victorious and has avenged his entire family, who you killed five months ago for their noses. Your first choice will be, in all likelihood, to smite the foolish little critter, but unfortunately this will take an alarming amount of time. For a mob so far below you in levels it takes a surprising number of strikes to defeat it, as it dodges and parries blows that have felled demons. If that was the only fight you had in a day it wouldn't be so bad, but within five seconds of having defeated the mob, his brother will turn up and launch himself at you with wild abandon, possibly with a yell of "Freedom from nasal tyranny!" as he does so. Five minutes and three hundred guinea pig corpses later, you decide that running away would be the least frustrating option, besides, you need to empty your bags of all these sodding guinea pig noses.
Can there be anything more heroic than a full-armour-plated warrior running in a straight line with a train of small furry animals chasing behind them, some of which are crippled from previous battles and others so old they're in wheelchairs?
Thank you MMO developer for immersing me in this game, for convincing me that grinding away on your carefully crafted world will enable me to improve in power to the point that I'm known throughout the lands, cherubs sing my praises, cathedrals are built in my honour, demons cower at the mention of my name and small furry animals with only three legs will still make me run like a schoolgirl to get away from them. You don't read fantasy stories where the adventurers are travelling from one town to another, and at some point a wolf jumps out and attacks, and then a bird, and then another wolf, and a pack of rabid guinea pigs and another wolf, and a giant bear and a sabre-tooth duck. And even if you did, you wouldn't get a description of how the adventurers bravely ran away (Sir Robin, I'm looking at you) with all this wildlife trailing after them across the countryside. If someone wrote a fantasy book based on an MMO, it would be five hundred pages long, of which one hundred pages are just detailing the adventurers fighting off an endless stream of crap animals on their way between towns.
One hundred pages would describe the adventurers trying to form a group with the right class/race mix. Hmmm, The Book of the MMO, I like it. Coming to an Inferno near you soon!
The annoyance factor of low level mob aggro is so high that eventually you think 'sod it' and turn around and shout "Come on then you irritating bastards!" at which point you realise that all the crap mobs have stopped chasing you, and you're left facing the elite Fel Koala of Grungmar who promptly pokes you a new ar... well, you get the idea. If you look carefully before you begin your corpse run, you'll see all the low level mobs snickering from behind a nearby tree, flicking V signs and thumbing their noses at you. Those that still have noses.
And let's not forget the joy of the gathering profession in an MMO. If you think you're safe now that you're gathering in an area that you've out-levelled, guess again, there are more ways to defeat an adventurer than mere combat. Try to mine that ore and the mob attacks, and even though they're so low in level that they're effectively vegetation they'll still manage to get a hit in and interrupt you so you can't finish the task. So off you run, because killing them is too tedious, and just as you break their aggro range one of their friends, who was waiting for you, picks up the chase. So you run back in the other direction, past the ore that you note someone else is now mining, and pickup the original mob and two more of his friends as you go. Eventually you give up, turn around to fight them... and there's the Fel Koala of Grungmar, wearing an evil smile and punching his fist into the palm of his other hand.