Because Sania is not Aishwarya/priyanka/sushmita/kim sharma/riya sen/celina//Shriya( )/Anushka( )
She may not be Rakhi Sawant, but sometimes one must exaggerate.
She is a average looking girl. Not ugly, but not hot. She is a tennis player. Let us appreciate her sporting skills, rather than trying to force something on her (hotness) that she does not possess.