I understand your sentiment and I to would love for them to all be viable at the same time.
However I am trying to be realistic about it. Just think about it, regardless of how balanced the game might be our idealogy as human beings is to classify, judge and label everything we meet and experience.
This is mostly why we create tier lists and such. This is also why riot is constantly changing the game to ensure that the meta changes to avoid stagnation and to keep us on our toes.
The reason we complain is that we want change of pace and not necessarily balance, but we want underdog surprises and we want the top dogs to be pegged down when they have been dominate for so long.
Rock, Paper and Scissor is a near perfect balanced game from a pure design standpoint, but your have outward bias such as inexperienced males always throwing rock first for instance.
So I guess Paper has a high winrate, but it doesn't make Paper overpowered does it?