What League of Legends needs is added Skin attributes...
I have been playing League of Legends for about a whole year now after having played a mobile MOBA called MOBA Legends. One characteristic about Mobile Legends that I really loved (and wished League of Legends incorporated) was the attributes associated with hero skins. For instance, one particular hero may have a skin available for purchase that attributed a +100HP stat, another +? armor, another atk/spd, etc. Now I understand that Runes was one of the reason that this wasn't done, but now with the advent of Runes Reforged that opens the possibility of giving skins some extra oomph in the absence of the old Runes system.
Another thing to think about, is thematic skins like Battlecast Kog' Maw or Battlecast Urgot an added armor attribute. Or Battle Boss Veigar, Battle Boss, Malzahar, etc could have extra AP attribute. You can even give skins more than one attributes as well.
Now, I love the skins available on League of Legends. I think Riot does a very good job with the art and aesthetic direction of their champions. However, aside from just being something nice to look at, the skins on LoL don't offer anything else of substantial value. So I want to suggest that League of Legends consider adding attributes/stats to the skins that we invest our time, money and effort into.