if you're a pro you should be able to play every champion in your role
Pro players have variety. And not every region has the exact same idea of meta game and champion picks. Robo's Darius. Archie's Sona. Both off meta in their own rights and a shake up compared to the usual. But not everything is completely viable nor trustworthy to what is beneficial to win. You can tread down the tier ladder all you want through the ban phase, but the further down you go, the more you resort to a pocket pick. That happens with a strong enough player or players of the same role quite often with the 10 ban system.
But what you're expecting and suggesting of them is to have variety that entertains you as the viewer instead of what benefits them to win the game they're putting their competitive careers for day in and day out, as short lived as that is for League compared to other Esports.
Plus the views are kind of what allows the game to be an esport. If no one watched the games then it couldn't be an esport.
How low would viewership need to be in order for it not to be considered an Esport? It already averages the highest viewership rate outside of major events from other popular competitive Esports and GDQ marathons if you count those. This quote you put sounds ridiculous if you really think of it. A fighting game stream can have 10k viewers at a time with just as much hype and be called an Esport. You're basically eluding to that if League were that low on viewership numbers to match that of FGC or even less popular shooters which account for lower numbers, it wouldn't be an Esport to that right. Someone will watch them and be hyped for them even if it's the same thing.
So doing something to make it more enjoyable for the viewers doesn't seem that unreasonable to me.
Again, my quote:
No other Esports game does that where you have to forcibly switch your mental state through character or weapon choices because of repetition.
This practically speaks my entire point right here. And this is why I disagree the most. Reiterating above: Because then you're not watching them play the best they possibly can as a team. You're just watching them play to either be entertained personally (and selfishly) or seek validity as a player of the game in what the champion can be good at given a pro playing it on stage rather than finding your own personal validity. And even then, that's a double edged sword in pro play as one side could run the challenge of a lower tier character into that of an all around high tier composition. See H2K vs SPY at the end of the EU Spring Split Reg Season for that one if you must.
I'm sorry if you don't agree with me. But I've been across enough games as a viewer with less of a character roster and seeing limitation of diversity that this is not necessarily a big deal to me in the slightest. Yes I do wish there could be some more balance and confidence among the players to pull out some niche picks like the Wildcards have done. But I'm not on board with outing Riot over it because it doesn't entertain the fans and will kill the Esports scene because in reality it really won't even if selfishness and greed overshadow everything. There's always someone who will remain interested as of the direction Esports is headed all together.