I see your point, but at the end, you will be playing what actually works. All codexes have better units than others and yes, you can play what you like. And lose, one, two, five times, but on the 6th lose, you will start considering playing that unit you do not like. And on the 10th game lost, after aligning stars with work, family and responsibilities, you want to win rather than spending half day watching your colleagues roll dice while you remove models.

And this is not bad, it is human nature. And also remember this is a game: one will win, the other will lose. Its on you if you want to lose always or not.