When you are in a society that values the exploitation of women to the point where a woman feels she is not beautiful or of worth to society unless she is naked, it is surely a valuable thing for women to be willing to provide themselves as examples that you can dress modestly and be beautiful.

You never know what might draw people to Islam. There may be women out there who think Islam sounds interesting, but feel that if they get involved with it, someone is going to shove them in a shroud and sack dress and hide them from the world. Then perhaps they see these women dressing modestly as examples and realize that Islam for women is not what they thought. It opens their minds enough for them to be more comfortable learning about Islam. Later, as they learn more, clothing and fashion will not matter as much to them anymore because they will have been able to learn the true beauty of the faith.