I don't think it is to do with magazine shots. Rather than carefully posed 'fashion' shots, what you are seeing is mainly people taking smartphone / iPad / PC shots of themselves. It's more to do with the kind of technology people are using to take pictures these days and fewer people bothering with 'proper cameras'. People with 'proper cameras' always took (and still take) a mixture of different kinds of shots from robo-pose to seated shots to men's magazine type 'action' pictures.
I'm sure this is it. It's also the time needed and the extra pair of hands required to hold and operate a "proper camera", or even a cellphone camera for the "photo-shoot". Location also comes into it as well, many people probably live in apartments without gardens or a good outside location to get those nice men's magazine type "action" pictures.
If someone has a "proper camera", it probably shows that they're interested or have a willing partner whose into good photography, as well as clothes.
Most of us probably only have our webcams, iPhones, filthy mirrors and squalid pink bedrooms to do our "fit" pictures with.
Edited by MikeDT - 9/10/12 at 7:50am