It's the Nine's fault.
After all, they created sentient life. KILL THEM!
No, Beth created the nine which created life. And we pay Beth for their games. It's our fault if one looks at it that way. A lore friendly way to look at it would be to consider just what the Elder Scrolls are. Aedra artifacts which allow one insite into the fabric of Nirn's reality. When mortals look at them, they exchange their vision to see what is and what could be. But without a Hero, there is no prophasy. One cannot exist without the other, and there always is a loophole.
Without a hero, there is no prophasy. Without the paying customer, there is no Elder Scroll game. Bethesda are the writers of the Elder Scrolls. But they create a loophole in everything they do.
The Scribes of the Elder Scrolls, Bethesda, needs to add a loophole in order to continue to hold onto their power as Scribes. Cause if there wasn't a loophole, it would just be a game where the world ends and we get to watch it happen unable to stop it. It would svck and wouldn't sell well. Beth would go under, and no more Elder Scrolls would be written/made.
So the Scribes add a loophole into everything they do, allowing an additional Scribe to enter into the game. Yes, there is a lore explanation for the creation kit and mods. We are that other Scribe. We create our avatar, and gain access to the TES world. Our very pressence can alter reality. The Aedra themselves can be bent to our whim if we so desirn modding it. Daedra can be created, or erased.
And it works both ways. Since we, the hero and other Scribe, are going to be in the game, there must also be a prophasy in which a hero is needed. It's our fault Alduin is coming to eat Nirn. By us simply being there, something has to happen. Otherwise it would be a game without a main quest.
Or in other words, what we're playing is the Elder Scrolls themselves. The reason they can't predict the future as 100% fact is because of us the player interacting with the world. We can choose what path to take, and even alter the world to create ones that weren't originally there. The workers at Bethesda are the Scribes who write/make the Elder Scrolls, and to keep their power they allow a loophole to enter the world, us, and give us the power to act as a Scribe as well. And through our avatar, which we gain control of when they should be dead, be that death a social one like being put in prison or a more a real death like being dragged to an underwater cave ala Daggerfall. It's why prisoners are so important. It's how we gain access to the world, by making someone who should be "dead" our avatar.
We are responcible for everything bad that happens in Nirn. We're also responcible for Nirn existing in the first place. So it depends what way you look at our role in the world. We could be looked at as a bad guy, what with all the things we bring when we create our avatar in Nirn. But without that avatar being created, Nirn wouldn't exist in the first place. And besides, with a flick of the wrist and the creation kit any bad we bring along with us can be errased in a heartbeat with a mod.
This game is basically one huge joke on the fourth wall.