I can't say I'm a fan of this idea. A video or 2 would be neat, but a full blown video series? I guess the SG hype haven't consumed my soul because that seems like a bit much.
We have to remember that the Star Guardian skins are just that, skins. Alternate fantasies of the original champs & those champs have their own stories (well....*looks at Soraka*...most champs). If anything, we need a League series for the canon long before we think alternate universes.
The canon should be the main focus of League's writers with skins getting love every once in a while.
Then you run into the issue of completely confusing ignorant people. Let's say this series does happen & non-League players are fans of it. When does fans come to the game to learn about their favorite characters, they'll learn that the SG versions aren't actually the main version.
SG Lux doesn't have the same story as Canon Lux, SG Jinx is not a crazy psychopath like Canon Jinx, SG Lulu looks completely different from Canon Lulu,etc. You'll end up marketing the wrong versions of the champs & some people won't like that. Especially since the version of the champs they like are locked behind a pay wall or grind & pay wall (they'll need to get the champ).
Let's not forget that there are League players who aren't fans of the SG skins, whether it be X Champ players who don't like the SG skin or players who like different champs in general. It would feel unfair for them that SG would get a series before their favorite champs & skinlines. If SG get a series, then everyone & their mom will be asking for a series about their favorite skins.
"I want one for PROJECT! I want one for Blood Moon! I want one for Order of the Fifth Age Taric! Etc." Riot will either give in & make series for every skinline. Or they'll don't & fans of other skins will feel like they're getting ignored.
I'm not saying SG shouldn't get any lore, but I don't think they deserve a full blown online show as if they're the main content of League.