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People enjoy the single player Elder Scrolls game on the PC because of the variety of things you can do on the PC such as modding! with moddings you can turn the game into your liking and it really adds tons of enjoyment into the game.
Elder Scrolls Online is an MMORPG, yeah I understand, I understand that the developers are afraid that some mods will give an advantage playing field in PvE and PvP but doesn't addon do the same? World of Warcraft doesn't allow modding because it is an MMORPG and yet they allow addons that give a person an advantages! an example would be "Deadly Boss Mods" is an addon that displays timers and warnings of a raid bosses spells and abilities! not just for raid bosses, but they have one that displays timers and warnings of a PvP players spells and abilities!
Now here is my suggestion as to how it could work! I will be comparing this to a program called Tmorph! anyone know of Tmorph? it is a popular program that you can use on World of Warcraft that allows you to change the appearance of your characters, including gears, hairs, and even race! When you do change your appearance, only you can see that changes! other players cannot see the changes that you've made with Tmorph! instead they see your default appearance! For example, say I have a steel longsword, using Tmorph, I can change the appearance of steel longsword into a bronze longsword! but other players cannot see the bronze longsword only I can, instead they see the steel longsword.
Most of fans favorite mods are mods that give new texture/graphics, new hairs, new looks, new skins, new faces, new eyes, new fan-made race, tattoos, piercings, new armor models that replace original and the list goes on and on. How is that going to give someone an ingame advantage? how is me using mod to change the appearance of my characters going to give me an ingame advantage? Now, just like Tmorph, they could make it work. If I use a mod for this new hair that I want to have that isn't available within the game, other players cannot see the new hair, instead they will see the default hair just like the Tmorph program, and in this case it does not have any affect at all to the onlline play. It doesn't give the person a slight advantage over the other person that isn't using the mod. You could say its only cosmetic.
Please make ESO moddable! it could work and it will work.
Nexus mods has over 150,000 different mods if you add all the mods from gamesas's game! so you can clearly see that modding is a big part of gamesas's game and it should stay that way. Just like Curse, I'm sure Nexus Mods can make sure that no mods will give an uneven playing field! the website itself is great and it even made it sure that their mods will not work on a pirated game.
btw I haven't gotten beta invites yet, still checking almost everyday.