So let's just stop here.
Let's assume, for just a second, that what you are saying is true. Let's assume (before getting into your multiclass hypotheticals, and your desire to optimize, and you need to put things into tiers, etc.) that you're right. That the classes aren't perfectly balanced, and won't be.
With that in mind, we can then get into the heart of the issue-
The fighter is the most chosen class. That means that people like it. They, to borrow phrase, can smell what the Rock is cooking. This is what they want.
Why do you discount what they want? Their opinions are just as valid as yours is. If people are getting what they want, then ... that's fine. Not everyone is you. It is not a fallacy to want something to different. Moreover, to tell other people that their opinions are "invalid" (as you did) or to claim that their desires are somehow the result of fallacious reasoning is the surest way to ensure that those people will most certainly not agree with what you're going to tell them.
As has been pointed out, it's not just what you say, it's also how you say it. Don't tell people why they are wrong- maybe, in the future, try and make a case for why people should agree with you because you're selling them something that they want.
I double-dog dare you to describe how totally awesome your favorite (game/playstyle) is, WITHOUT comparing it to any others.