Or, do you?

Zileas is leading them in intensive delving meditations upon the nature of widely appealing storylines.

Patience!

At least they're trying, unlike other companies that make the story 'just good enough' to sell copies, rather than a lasting franchise.

What, you don't know? Riot FIRED just about everyone on the lore team, because there were no profits to be made in them.

I love the lore because there's no 'And this is why they joined the league of legends' clause in it. She wanted to beat the living sun out of everyone, and here's where she's going to do it.

We can infer that she must have joined the league.

You completely missed the point of her lore... Her elders were fanatics, extremists, they've smitten anyone who's dared to doubt the sun or deny the sun. Diana felt in harmony with the moon and dusk, therefore she tried to talk the elders into seeing if there was people who worshiped the moon or if they acknowledged it. But the elders rejected her and made her feel like an outcast. She then made research and found this temple, there she found a lunar armor and a crescent blade, she comes back to her tribe to show them her discoveries, only to be hated and betrayed, they sentenced her to death for doubting the sun and basically sacrilege for going against the sun with its opposite, the moon.

So they sentenced her to death and the moon intervened, she then killed her assassins, which I would've done the same.

Well, they do often state why a champion joined the League, which is fine.

For some champions however, they could do a little bit better on the why they are fighting in the League.

Nautilus and Lulu for example are pretty strange storyline additions.

Diana it's pretty clear that she wants to demonstrate the supremacy of the moon, show people the 'truth', that sort of thing.
(And presumably, as the storyline goes, if she tried to start a war elsewhere, a bunch of Wizards would stop her.)

Nautilus wanted revenge against the people who left him, the League said "no", and, he decided to stay and fight anyway?

Maybe Lulu fights for Bandle City, but that's not really the clear. She just sort of tripped out of the woods one day.

What about skin ideas and such? Quite a few of those likely came from lore ideas.

As a note, I (as well as a fair few screenwriters) could write a miniseries screenplay out of that concept in a couple days.

You've got to make sure the story fits well into the flow of the world itself, and not just as isolated snippets.

How do Diana and Singed get along?

That sort of stuff.

The world should feel alive and progressive, and give players a very clear feel for the flow of things.

Warhammer 40k is one of the best franchises at this particular mechanic-- the feeling that things are happening behind the scenes and not just on stage.

What? That's a baseless assumption. Who do you think Runaan, Harrow, RiotRaven and all the other creative designers who post on the forums are?

You sir or madam are a player after my own heart. Sign me up.