Perhaps this has been discussed in a time previous to when i was playing league of legends, but i think a campaign would be a really cool idea. I like lists so I am going to lay out a list with some ideas.
Overview: I think it would be cool to have a campaign in the same style that the old Mortal Kombat games had a campaign. The campaign would entail a series of games played against certain teams. I think there is a lot of design opportunity for that part. We already have story, and i think it would be a really cool way to incorporate more story, and for the people who dont read the lore to learn about the characters.
1. I think the use of campaign would also encourage players to play more practice games. I cannot claim i have never joined MM with a character i havent used, but everyone is always crying about the fact that people need to join practice games first. I think a campaign would help tremendously.
2. The campaign could force the player to use the free champions for the week, or other champions they own. Maybe create part of the campaign for characters that they have to use, and the other part they can choose their own. I am not sure if this would be hard from a IT perspective, but if its possible, i think it would be interesting.
3. Also, when i first joined the game, like a lot of people, had no idea about anything. I didnt know what a carry was, a gank, etc etc. If using a script is something Riot would be willing to do, I think familiarizing the players with those words could be incorporated into the script.
This list isnt as long as i imagined, but thats not the point. What do you guys think? Ideas, suggestions, or just rude comments are welcome. Discuss!