Merging Accounts
Smurf accounts are inevitable. People make them to play with friends, try out new things, screw around with "Only maining <champion> to <rank>" and even to play anonymously. I think that a solution to the large number of accounts taken up per unique player would be to offer a service to merge player accounts so that a single login can allow you access to more than a single summoner. This feature would be akin to the character selection screens of MMORPGS where you have a single account to sign into the game, but each character/summoner would have its own unique champions, skins, runes, levels, and statistics separate from the others.
My idea is that the box where the summoner name is located (the thing that shows your experience bar and name) be changed to have a drop down menu to select from multiple accounts that could be merged through a multi-step process that requires authorization from email addresses to insure proper security. Riot Point wallets could be merged for the entire account, but have IP separate per summoner, similar to the way that in game currency would be unique to the character in an RPG, but account purchases would affect all the characters on the account.
Smurf accounts will never go away as long as it is possible to have more than a single account per verified user, but by making the creation and perhaps even deletion of smurf accounts easier, it may be possible to make the system less abused.