No. All cultures are not equal.
In my Communications class, our teacher told us that ethnocentrism is bad because no ones' culture is superior to another.
Of course I was taken aback by such a statement.
There are things that cultures do that we would find immoral, slavery, persecution of homosexuals, etc.
All things equal, a culture that practices and/or supports things like those, is not equal to one that doesn't.
We are better than them.