So... Ezreal is not among the Shurima-associated Champions despite his gauntlet...

Ezreal is Piltovian. Including him in the Shurima lore update because of his gauntlet would be like including Sion in a Demacia lore update because his jaw is Jarvan I's crown.

doesnt he originate from piltover?

Because Ezreal is just a tomb raider that took something from Shurima. Like Cassiopeia, hence why she doesn't show up as well.

he is from piltover so thats were he is connected. i mean olaf is freljord but he goes raiding everywere he pleases doesnt mean he is connected

From the looks of it I think it is likely that they'll make a site like that for every region eventually,which is likely the first step of them to make the lore more accessible(because you could simply look at the site of the respective city state to find all the lores connecting to it,maybe they'll even make an interactive map once they made something like this for all the city states).

Ezreal will likely be accessible on the piltover site,because even though he got his gauntlet in shurima,he is still a piltovian. Likewise Cassio will likely be on the noxus-site and Malzahar&Rek'Sai on the void-site.

Yeah, upset that he is not getting extended lore after being a year without it.

Well, sure. If I show up wearing a Swiss watch, I'm not from Switzerland am I?