Playing League of Legends again after over a year off has been interesting so far, and very entertaining.
At it’s core, it’s still LoL, and I do enjoy that core immensely. This isn’t like going back to World of Warcraft post-TBC and playing welfare-epics Online, where the game you left and the game you return to is so fundamentally different it now caters to a completely different audience. No, LoL is not any easier, or ‘dumbed down’, than it was years ago. You are still rewarded for learning how to last-hit in lane, having map awareness, positioning, solid timing, and all the other skills that separate LoL players into the various ranked tiers.
At the same time, the amount of ‘stuff’ surrounding that core is kind of ridiculous. There are currently 143 champions. That’s just an absurd number, yet at the same time doesn’t feel like a bad thing. You don’t need to know how to play all 143, and so long as you have basic knowledge about all of them, you can face off vs them at lower ranked tiers and usually do fine. Runes have been reworked, and there are now more choices to make, while at the same time the biggest impact decision is limited to one keystone that everyone can see. Learn the keystones, and you have 80% of the knowledge you need outside of the upper skill levels. The map is 95% the same, and the small changes you can learn as you go.
On the fluff side the number and quality of the skins has of course increased, so its fun to see some of the more impressive skins in-game. I’ve yet to purchase more RP to grab more skins myself, but it’s coming. Plus there are now daily and longer quests that reward blue essence (the free currency), chests you earn that can give you champions or skins, a different honor system, changes to the reporting system, and who knows what else.
What I think is most impressive is that right now I can say that LoL is in its best state. It runs perfectly, everything is snappy, and the polish is off the charts. A new player joining today isn’t late to the party, and they don’t have to climb a mountain to catch up like in many older games. They just get to enjoy a better version of what was always a top-notch game, and from a development standpoint that’s remarkable.
Hardcore Casual 
“You don’t need to know how to play all 143, and so long as you have basic knowledge about all of them…”
I want there to be some relation to Dunbar’s number in this. But I suspect that of the 143 possibles the meta dictates that there are some you are more likely to see than others, with a small group you probably see nearly every match. How much do you think you would have to play to see all 143?
I’m still climbing out of one-armed-baby ranks, but down here I see a surprising amount of variety in all roles. Here is a site that breaks down usage in way too much detail: https://nexus.leagueoflegends.com/en-us/2017/11/champ-popularity-mixing-math-art/
That said I’d guess a lot of games are needed to see all 143, just because 143 is a large number in a game with 10 champions in each game. But that’s not because some champions are never played, or that the top 20 ‘meta’ champions are in 75% of all games.