So I want to add some thoughts to this and comment on it because I believe there is some misunderstanding in this whole mess.
First, stuff like Ardent and Janna should have been fixed before Worlds. I completely agree. The issue is not that they didn't change this during the Worlds patch, it's that they didn't change it prior. These problems we are now seeing at Worlds was a big issue with the game prior to the World patches even coming out. The problem was that we let them linger for far to long and the World patches really highlight the problem in full force. Riot fucked up and didn't act more aggressively towards the problems before they headed into Worlds. That is the issue here.
Second, the play you are talking about had more factors than just Janna. I saw the same clip. You cannot overblow that play and say "LOL Janna+Ardent no counter play." No. Galio used his ultimate and Janna had to blow shield and Ultimate to keep Kog alive and the damage done by C9 wasn't that impressive to begin with. There was a ton of things at play and this wasn't just caused by Janna and Ardent.
If you want a better example of how powerful those things were, just look at the current Worlds meta where everyone is using Relic shield to rush to Ardent. That is a good example of an item having too much priority.
Finally, the issue about Pros being able to adapt. Now league is an ever changing game and players are told to adapt to changes rather rapidly. The main reason Pros aren't asked to do this is because it gives teams and players the time to focus on the current meta a lot easier while developing ways to break it and what they can do. Sometimes that results in various counters or different picks that we could never see. The Noc pick. The Morde. All of Misfits supports. A ton of these picks would not likely be used because teams would default to the safe and reliable. Pros aren't playing on PBE or anything, they are on live so the bigger the changes, the more likely players would need to adjust rapidly.
Take Azir for example. If Azir was put up during the Worlds patch, he would be so strong that likely every time would need to pick or ban him. Anyone that has played Azir would be a lot strong while others who aren't as capable would start falling flat.
Many teams that practiced with Ardent would than need to rapidly change their bot lane set-up to what is the best and most powerful. The game than isn't decided by skill but which team can adapt the fastest. Now that isn't to say that doesn't have some kind of skill involved but it would be chaos with clear wins by teams that can quickly understand the new meta. Now that isn't to say that is bad, it really isn't because there is already some of that in the worlds meta. But it means a team that practiced, practiced, practiced with a certain comp, game plan, could have that completely thrown out the window and lost because what is now OP isn't what they practiced. Because what is now OP wasn't what they played to counter.
Now is it perfect? No, I don't believe it is. However, doing something that gives Pros the time and practice they need so they can adapt to the current meta and figure out ways to break it and give other teams a run for their money, that is good. No other sport, e-sport, game, whatever really ever makes massive changes around their worlds meta because of the same philosophy I just talked about above. By keeping everything in the same place for a month prior to their worlds, it gives everyone an equal chance to learn that meta and keep their skill as the most important aspect of the game. Not who can adapt the quickest.
Ardent and Janna and a couple of other factors were a big issue this worlds but they were issues prior to the worlds patch. We should not punish players because of Riot's fuck up. Instead, blame Riot for acting slowly. Hold Riot to their inability to act quickly. That is what we should be talking about. Not that these problems are at worlds. That these problems were even allowed to get near the worlds patches in the first place.