I don't know what material would be better other than actual armor. But that opens a door to a lot of other practicality-issues regarding the process of actually making the movie.
No rubber = no armor.
And sure, that is a way to go. It's just not the way they went. And based on the storyline and the realistic approach I can understand their decision.
It sounds like you actually accept make-believe muscles over make-believe armor?
Perhaps this is why we disagree.
I accept the armor. I think it adds to the concept and the storyline. I think they have went for a realistic approach and it would somehow be unrealistic that an otherwise clever guy would decide to fight crime without protecting himself. He doesn't use guns. He can't shoot back. And that makes him a target.
While a comic book character may choose an unrealistic approach to crimefighting I don't think any real person would. And I think they are trying to make Batman as real as possible. They are trying to make him think and act like a real person, not a comic book character.
So you will accept armor if it is hidden or looks more human? Ok, but why would a masked crimefighter care about hiding his armor or going out of his way to change it's shape? It would have no practical purpose to go for a certain look.
I do see your points also. But I think you are asking for a different type of Batman that would also require a different type of storyline and a different type of movie all together. And while this would certainly also be a way to go, it's a bit too late by now.
So let's agree to disagree.

t: