Survey participants were asked if they feel attractive when wearing garments. I included in parenthesis "physically and/or sexually appealing" to clarify this question, but I think there was likely some variation in interpretation. Ex-Mormon women were told to answer how they felt when they were active.
There are many variables that affect how we feel about our physical appearance, so I don't think we can draw a direct line between garments and feelings of unattractiveness, but the numbers show that garments do have an impact for many people.
One of the most interesting things I read in the submitted comments, was that many active LDS women felt that it was "worldly" to be concerned with physical appearance and that garments help to remind you to focus on other things. This is contrast to the BYU honor code, missionary dress rules, and dress guidelines in the For The Strength of Youth pamphlet. The church has historically put emphasis on the outward appearance of its members, but there seems to be some parameters of when that is appropriate and when it becomes "worldly."
Another interesting theme from the comments was that many women equated feeling attractive with being fashionable or trendy. They expressed that LDS women are "set apart from the world" and don't worry about fashion and trends. I found this intriguing because feelings of attractiveness or sexual appeal are not exclusively tied to trends, although they can be.
The top image is the results from the entire surveyed group, and the second chart is just active LDS women: