I don't agree. Most mods are from people who do create textures and custom models which is ok at best. I've seen some pretty lousy textures in some pretty popular mods. Placing premade items and changing values on items isn't such a bad thing. I created a mod for Fallout Tactics: Brotherhood of Steel, and all I did was change a few values and add in alot of new items using exsisting textures and models, and it turned out awesome. In fact most mods used to be created without importing user created textures and meshes, but it seems that most people here don't remember that. If you think that a mod can't be made without using custom content, then I feel very sorry for you. Also my question about the release time for the G.E.C.K. was last reported as comming out in August of 2016.
I'm also guessing that most of the people answering here don't actually have any real experience making mods or using the creation tool, but they sure like to talk like they know what they're doing. I've been using the content creation tools from all of the 3D morrowind games, as well as Fallout 3 and Vegas. If you think its hard, then you shouldn't even consider using it. Also, the creation kit can pull from the disc or the install folder I've seen it done ALOT before, all without using folders outside of what the game created. I've also created content for quite a few other games over the years as well.
As for a keyboard and mouse, thats easy. Just get a USB mouse and keyboard. It worked for me with the Xbox 360, PS2, PS3, and yes, the Xbox One. This isn't rocket science people, quit acting like it is! As for why I know so much, that comes from ACTUAL experience. I have actually taken classes to learn game creation, and texture creation (among others) I've also played more games than most you. Why do I say that. Well, because I own over 10,000 games (not including indies) I have played almost 60,000 games so far in my life, and am still playing more. No, I'm not very old, not fat, not a loser, and yes, I have a life as well. I have also played and still own, Fallout 1, 2, Tactics (not the console version one) 3, and New Vegas. I even got to play the unreleased Fallout 3 that never saw the light of day!