I agree with your concern. When guys show their hip line and the brand of their boxers on purpose, then why should we be ashamed of a piece of cloth showing. No one points out those guys but we girls are called shameless for the same reason.
I’m a muslim who covers herself from head to toe yet I don’t get it how people are so judgemental about bras and parties showing! And why is it considered as a bad thing? Just why? As you said earlier, its a piece of cloth covering your body. THAT. IS. IT.