My theory for why a later game meta is funner to play
Ok, so let's say that the game is "decided" at minute X, and it takes Y minutes to actually end the game, well the whole point of league is that those X minutes are fun, whereas those Y minutes are not.
Currently, games are often decided around ~10 minutes, but end at around 25 minutes. This means that for the first ten minutes, you will be able to have fun (arguably, sometimes the game is decided in champ select, or by trolls/inters/ragers). But for 15 minutes, you will not be having fun, this means for over half the game, you are probably not happy. This does not make for a good experience.
But that also means you will probably not have fun for the next 15 minutes. Yes, there is a small chance that you will comeback - but the fact is (at least around Plat), people have almost no clue how to play from behind - and especially with the changes such as vision removal they will probably chain feed until the game ends.
Now the thing about a late game meta is this: Let's say games average around ~40 minutes.
The way league works - its much easier to close out games the later it gets. So if the game ends at 40 minutes, it was most likely "decided" around 35 minutes (because with the power of baron/elder it will take max 5 minutes to close out a won game - also assuming that they've already taken down some outers/inners)
This means for 87% of the game, you are having fun - or at least it feels competitive.
However, games CAN get too long - if games start lasting ~55minutes - then suddenly it feels like all your early game efforts are worthless. One teamfight win, regardless of how behind they were - will most likely decide the game. So whats the point of even trying in the early game.
Those are my thoughts.