What if there was a story mode where people could complete campaigns and quests to unlock new champs and get IP and EXP, and etc. Like you would have scenarios where you would have to defeat yasuo, or etc. It can allow people to learn to play the game mechanically, and improve new player experience.
What about.. "Lore mode"
You go though the characters lore up until they join the league...
Something you can do by yourself without other people ruining your experience... Who knows.. it might inspire something..
While that might be fun, there are a few issues.
Development Time: That would require a HUGE effort on Riot's part, which would take away from development power for Summoner's Rift and new champions, which is what drives most of the gameplay on League of Legends.
Economics: Spending a large amount of money to develop a single-player mode that gives away champions and more IP isn't really a financially viable option and Riot is, at the end of the day, a company that wants to both stay in business and grow.
