I find it interesting that people get so hot and heavy about Riot possibly doing something in the intent that it would generate them money. They are a business, that was what they were created to do. And 99% of the time, the thing isn't even something that is immoral or unfair!(see: people complaining about how Hextech Crafting was a way to get people to spend more money. Seriously, what?)
If Riot does release overpowered champions on purpose with the intent on gaining money, so what? As long as the champs are not breaking the game at the seams, and are brought back into line fairly quickly, is it so bad that Riot generated money to continue developing this game? If you have a problem with it, don't buy the champ with RP.
Now onto another point, can you actually expect a champ to be perfectly balanced when the testing is limited? Which would you think would paint a better picture of a champs power, 10, 000 testers(if that), or several million?(spoilers, it's the second). The PBE isn't a "make sure everything is 100% balanced and has absolutely no issues" mode, it is a "make sure that everything works as it is intended, and that it isn't absurdly broken" mode. When your goal is to make sure the coding behind a champ actually applies all its effects correctly without any bugs, making sure that it is balanced against every other champ, in every combination of builds, kinda takes the backseat.