Don´t end your friendship with them, Ramya! :) Although I agree they were rude (and I think they would have stopped if Brandon would have pay heed to the comments and shaken it off with a smile), there was room for rudeness in such a polite society.
I´m always shocked when I read, for example, Brandon in chapter 11, asking Elinor if her sister of 17 would consider second attachments. What??? They´re not long standing friends, they´re no relatives...Isn´t it rude of him to talk about Marianne´s or other people´s feelings like that? For me it´s quite out of place. But I´m sure it was quite accepted at the moment, like discussing money or beauty.