Login rewards and in-game missions are one way to keep players to stay active in a game, and Riot Games is finally picking on as they are looking to implement Missions in League of Legends, not that there are less people playing the game though. It is also another great way for players to earn awesome rewards like Champion skins, Summoner Icons and many more after completing a mission.
Back then, Riot had no plans on implementing the mission or daily quest system as it can potentially affect a player's performance in game. For instance, if the mission tells you to play a certain champion for a number of times to earn a reward, that hero might be one of those who have fallen out of the meta or does not fit the team composition well, and your teammates might flame or report you for trolling. However, they came up with a solution to make missions not affect the game, at least not that much.
Here is what Riot Revenancer posted in the Developers Blog:
WHAT WILL MISSIONS BE LIKE?
Missions will offer players new challenges to solve on the Rift for rewards like unique skins, Summoner icons, and loot. Since this is uncharted territory for League, we don’t quite know where we’ll end up years from now, but we do have some guiding principles to separate a good mission from a bad one.
PRINCIPLE #1: MISSIONS DON’T TROLL YOUR GAMES.
PRINCIPLE #2: MISSIONS CHALLENGE YOUR SKILL, NOT YOUR PATIENCE.
Ultimately, we want players to come away from a completed mission having had fun—or feeling satisfied with the challenge they’ve overcome.
WILL LEAGUE BE ABOUT COMPLETING MISSIONS?
Rest assured, League of Legends is first and foremost a PvP game that’s about battling it out on the Rift. It isn’t an RPG; we don’t want to make the game about questing or checking boxes off a list. We won’t be flooding the game with a deluge of missions just to keep shaking things up.
Our goal with Missions is to deepen all sorts of aspects of the game you already enjoy. Now regions and feature teams have the flexibility to add missions that enhance your experience with new goals and rewards. You might be able to do a chain of missions to demonstrate your loyalty to TSM (or CLG, if you’re a masochist like me) and earn a unique icon, or live a new champion’s story personally through a set of missions.
We’re just starting with Missions, and we’re going to start small. Ultimately, what you guys think of the feature will determine its place in League, so definitely leave us feedback about what you like—or don’t—as new missions roll out.
It's really nice that Riot is adding Missions to League of Legends but they did not mention when will it hit live servers, or at least the PBE first. Hopefully it will be as soon as possible.