Adding more permanent maps
This post is a response to Ghostcrawler on ask.fm. 300 characters is not enough. Feel free to read for fun if you want.
While many of my posts don't have too much thought put into them, this one I know a significant amount about, as I have worked on over 100 team pvp maps to varying degrees. Because it lies close to my heart I will be resending this to you on your ask.fm until you inform me somehow that you've read it. A proper response is unnecessary and unexpected with how busy you are and how time consuming responding is. My only goal is to open your mind and with it, Riot's mind to new possibilities. "Hi!" would be fine.
The main reason why TT and Dominion are not as popular as Rift is because they are the same map. Comparing to champions, Vel'Koz and Xerath are the same champion. They deal damage to multiple champions with longranged skillshots from a distance, and have a bit of CC. The few things that set them apart are very small.
Rift, TT, Dominion are all maps where there are 2 teams in an equal planning situation, fighting macro strategically with mechanics to win. TT has less people in a game, but it's still the same thing. Dominion has a different objectives system, but it's still the same thing. What sets the maps apart is only the outer skin, at the core when players play these maps they're doing the exact same thing. The only reason why Rift is most popular is because that's what Riot has centered league around. If TT was the map for ranked, LCS, balancing, then it'd be where Rift is now.
It is fine to have that one core with lots of different skins. HotS uses that system for maps I believe.
ARAM isn't included in this same core though. The random aspect along with the constant teamfighting, linear nature, and mayhem of ARAM make ARAM a different game. It's a map where 2 teams are put in an equal random situation, fighting with micro mechanics and basic strategy to win. TT, Dominion, and Rift are not really chaotic, but ARAM is.
All the temporary gamemodes that Riot has released so far have usually fallen because of them being the same core as well. URF and Nemesis, One for All, all the same as Rift. Poro King is a bit of a hybrid between Rift and ARAM. Ascension and doom bots are the only ones with a touch of hybrid to something new, but since everything else is still the exact same and even a bit simplified it has no effect overall.
If Riot wants to add more maps, then they need to break the cycle of having them be the same core. On top of that, they need to condense queues so that Rift is less spread out. By removing Classic Draft for TB Draft and Blind for TB Classic we'd be good to go.
For example, Riot could add a map where 3 teams fight in a planned situation with strategy. This gamemode would need to be supported by LCS with some kind of high level tournament to ensure the development of strategy and an end-goal for players of the gamemode. The added dynamic of 3 different parties would change the core of the game. This map could hold a consistent strong playerbase as a result, definitely if LCS supported. If not though the increased strategic demand along with the similarities with Rift's core could lead it to being less popular than expected. It would always hold a playerbase bigger than TT and Dominion though.
The most guaranteed approach in my opinion would be to put teams in uneven circumstances. For example, a 5v3 map. The 5 get random champions shown to the enemy, and then the 3 get to choose champions to face the 5. The 3 also get significant advantages in the map itself. This approach would be guaranteed to have a completely unique core as a gamemode, and could uphold a strong playerbase at least roughly equal to ARAM if not significantly higher depending on Ranked and LCS interference.
To summarize, League of Legends has the option to have additional maps/gamemodes which can uphold a strong playerbase for a long time and be played regularly if the maps/gamemodes change the core of their gameplay to offer the players something new and unique each time.