I agree w/ Hersute that we'll often see these swept back styles posted due to curiosity about the realism of the hairlines.

I would go even further and suggest that, for me, the fact that realistic hairlines are readily available w/ pieces these days, leads me to show the front to "offset" any areas where the piece may be more detectable. In my case, it's the blend at the back and sides. Exposing a realistic front seems to suggest, "see, this can't be a hairpiece ..." It's the same idea as using products, highlights, and bold styles that the general public wouldn't associate w/ wearing.

I "lead" w/ something so natural looking, that it doesn't invite too much scrutiny into the aspects of a piece that might be less natural ... color, density, texture match, etc.