The world of Runeterra is getting smaller, not bigger
First off, let me say that I am NOT a player of Twisted Treeline; I used to play it back when my brothers still played this game, and because there were 3 of us, we were able to make a team perfect for the size of that mode and I avidly played it then. Since they stopped playing the game, I thus stopped playing TT as while I'm not saying the teammates I got were bad by any means, I just didn't have the same level of synergy with them in comparison to when my brothers played. BUT, that does not mean I oppose or dislike those that seek to have the 3v3 mode be retained in the game rather than removed. In fact, this is a post in support of their aims to keep the mode in LOL.
There was a time when the playable maps in LOL were intended to represent a tangible place within the world of Runeterra, aside from Summoner's Rift (And some could say the Kalamanda Map for Dominion, which has become the map for the Shurima Desert with the "Ascended" RGM). Freljord (As well as Bilgewater now with Butcher's Bridge) has a "playable map" in the form of the Howling Abyss. The Shadow Isles were supposed to be represented in the form of the Twisted Treeline.
By removing TT, Riot is actually SHRINKING the size of their in-game world as (Based on at least what I understand in the new lore) Summoner's Rift, in a sense is NOT a literal location within Runeterra anymore, while TT is (Or at least WAS), like I said above, supposed to be a literal area within the Shadow Isles, akin to how the Freljord LITERALLY is supposed to have the Howling Abyss bridge as a location, as it is where the defeated Watchers were cast into the depths of the abyss. Where these places are literally located WITHIN those areas was not supposed to matter; it was just intended that they were a LITERAL LOCATION within that region. They gave us a general idea of what that region looked like. No, not EVERYWHERE in that region, whether it be the Freljord, Shadow Isles, or Bilgewater in the case of Butcher's Bridge would look like what is depicted in the map; it was just the general aesthetics.
The Howling Abyss gives us a general idea of the cold, constant snow and hardships the people that live in the Freljord deal with on a day-to-day basis.
The Butcher's Bridge gives us a general idea of the ramshackle haphazard building styles of Bilgewater, since buildings are literally supposed to be made from leftovers of gutted ships and whatever else of makeshift materials they could get their hands on.
And with the Twisted Treeline, we were given a glimpse into the former Blessed Isles, and how the Ruination so utterly transformed it into the deadly foreboding place it is now, the Shadow Isles.
By removing TT, we now only have 1 CANON place in the world of Runeterra that we can play on; The Howling Abyss, or 2 if you count the times it is switched out for Butcher's Bridge.
If you're going to be focusing entirely on SR and TFT Riot, then I suggest you start creating new 5v5 maps if you want us to believe that Runeterra is REALLY as big of a world as you say; because if a person knew that the Howling Abyss is the only CANON location within the game they would assume that Runeterra in is the depths of that planet's Ice Age.
EDIT: I did not mention maps used in things like the Star Guardian or Odyssey Event Game Modes or others (Such as the PROJECT game mode, I don't remember the name of it, or the Dark Star Event) because those places are not supposed to be CANON locations within the world of Runeterra; they are supposed to be alternate universes and thus have no real connection to the ACTUAL PLANET of Runeterra as it is supposed to exist within the lore.
GL and HF in your games.
