Contrary to what people assume when I complain about alts, and having to create one just to play a different class/alliance/hair style, my dislike of having to create one does not stem from having to level them from 1-50 (well, maybe the skill lines, but those Lorebooks took way too long, dammit!).

Here, I will explain precisely why I hate the idea of making another character, and things that I'd change if I was the one calling the shots to make things less irritating.

Skill Lines

I'd understand if it was for skill lines I hadn't already levelled on my main (skills for another class, weapon skills I didn't specialise in, etc.), hell I understand for the rest of them too. It's just....annoying. I mean, say you had to kill 50000 enemies with a two handed weapon to max out the skill line, and say I had gotten to level 50 in that skill line on my main. I'd already killed 50000 enemies on my main, I hate the idea of having to kill another 50000 on my alt just to get back to the point where I was.

To make this less irritating, for skill lines that increase based on experience, AP, inspiration, and reputation, if you already have a character that's a higher rank in those skill lines than your current one, you gain a boost in how quick you level up that skill line, but only until you get to the point where you were on your other character. As an example, your main is level 43 in smithing. If you create an alt, they will level up to 43 in smithing much faster, but will level the normal rate from 43-50.


Skyshards

I'll be honest, it took me ages, but I managed to find every skyshard in the base game, plus a bunch in the DLC. That's something I really hated doing, but I did it anyways because it was for the good of my character. I really hate the idea of doing it a second time, or a third time, or a however-many-times-I'm-going-to-create-an-alt-on-this-game-th time.

If it were up to me, I'd make it so that once you'd gotten a skyshard on one character, you had it on all of your characters. The same applies to skill points earned by hunting them. When you create a new character, you'd have a lot of skill points to spend, just like champion points. It'd be something of a reward for getting all of the skyshards.

Lorebooks

I hate this for the same reason I hate hunting the same skyshards.

I thought briefly about the possibility of making them account-based as well, but then I realised that wouldn't work due to the fact that they are directly tied in with your reputation in the Mages' Guild. I then thought about it some more, and thought of a solution. It's a little convoluted, so please bear with me:

The first time you grab a book in Shalidor's Library, it's there across your account. It also disappears from the overworld on all of your characters. Picking them up adds to the Mages' Guild reputation of the character that picked it up, not the whole account.

"But once all of the books have been collected, that'll make it impossible for new players to gain reputation!" Well, I thought of that. How about a repeatable quest, one where the Mages' Guild send you to recover one of the Lorebooks? It'll pick one at random from the zones you've already visited and, if you've already obtained it on another character, it'll place it there for you to find purely for that quest. You would essentially gain rep in the Mages' guild by doing this repeatable quest.

Recipes

Worked my ass off to get that Psijic Ambrosia recipe, I really don't want to have to do that again. I know I could just have the character that has the recipe craft it for everyone, but that's just hassle I don't want to have to go through. Plus, I'm a completionist, so...

I'd make recipes account wide, or at least allow characters to write down recipes they knew for other characters on the same account to learn.

Trait Research & Crafting Styles

Same as with recipes. Think about all the research time that's been put into your character, now think about all of the crafting styles that character has learned. The crafting styles would be incredibly costly, and the researching would take AGES.

To make it easier, I've come up with an idea for an item called a Memory Stone. Basically, a character will use this to store memory of a style or trait, and then another character would be able to use that stone to learn said trait/style instantly. They'd probably be account bound, since if they could be traded the guild stores would be overrun by them in less than a day.

Conclusion

That's pretty much it, all the reasons I hate the idea of starting a new character.
The top two are easily the biggest pain in the ass, and I don't think I could even consider starting a new character unless they were dealt with in the future.