Small change that would mean a lot
When we select our champion, have it immediately replace the banner on the left with the skin we have selected (if we own the skin). Instead of waiting until game launch.
Additionally, have the champion icon change to reflect the new portrait (like it does in game). You could also change the portrait ingame at the score screen.
Two reasons: 1 Because we like the skin we bought and prefer seeing it replace the normal skin whenever possible.
2 Because this would make it easier to see what skins your team has and pick one that will match them, being able to see what they cycle through and have more time to see what they've picked.