The point of the game is winning it.
Ranked games are there to "tryhard", meaning that you will focus your attention on winning the game using mostly strategies that have proven to be efficient, in other terms, using the current meta to win. Your mastering of the current state of the meta will be shown by your rank, and this will prove that you have understood the current game's mechanics to a certain degree accordingly to your division.
Normal games are different. In normal games, your main goal will not reside in winning, but finding and experimenting new ways of winning. It's a sandbox ground meant for finding new ways of playing.
On top of this, it also means that you will find friendly matches. Friendly matches are about winning, do not misjudge their meaning. But their main reason to exist aside from being a testing ground for new strategies, is to bring players together for amusement ; in other terms, it is not a demonstration of particular mastering of the game.
If you go play normals, it is like you're going to play in a friendly match of football. Everyone's invited, we play for the fun, and at the end there's a nice meal for everybody. In LoL, it means that you will pick a champion that is not meta and/or at a non-meta role and/or with a non-meta build, start the game and try to win your game with the new rulesets you have imposed by the choices you have made before. While you respect the only rule of the game regarding playing style, aka. destroy the nexus, you're fine.
What brings so much misinterpretations and lack of understanding between each player mindset is that these two concepts are indeed not differenciated in that queue. There is no "Serious experimentation queue" and "IDC I just want to have fun" queue.
What could fix this drastically is creating two separated queues for each playstyle. But there is another and smarter solution : introducing a system that matches players who have the same goals. In Halo:Reach's matchmaking, there was an optionnal mini-form you could fill before starting to queue, with your playstyle, how you communicate and your goals for the next games (winning or having fun), and you were more likely to get matched with people sharing your choices in the form.
Importing this into LoL could extend waiting times, but since it's optionnal, you could leave the form empty and you'll get matched faster, with either people who want fun or people who want to experiment new strategies (this also opens the possibility for players who leave the form empty to get more punishment if they flame, because they could have filled the form and not get matched with people they don't like the mentality of, instead of leaving it empty and complaining after).