I think it should be sober rather than Formal all time.In BD for gents Formal dress means Full sleeve Shirt and Black Pant and for Girls three pieces and to some extent Saree.I think as the students spend a long time in the university so they should wear something which is comfortable, modern and sober at same time.Formal dress may be for the Presentation ,interview board,viva board.I do agree with Mr. Siddique it should be comfortable both physically for the person and mentally for others.The main thing is selecting the dress ( Color, design ,Size, fashion ) and the way u r putting the dress on you.The same dress may look different depending on the way of putting on.It is not true that only costly dresses are always good to see, u may buy a dress with a moderate price which may look far better than any costly dress.