I have to agree strangely enough with all of the above. For me it's a multiple of reasons that work with each other:
1) Romanticism - Nobody should be able to deny this; Romance makes us fools and fools do stupid things, and to leave a warm and save house and hot meal to go and struggle outdoors for less than that for many it will sound absurd and stupid. But,
2) Genetic - It's something that has been imprinted in out DNA for millions of years (first tool ever found dates almost 2,000,000 years ago -
http://www.bbc.co.uk/ahistoryoftheworld). It is therefore something strongly inprinted in our genetic code and as such, since we are the first few generations that are completely isolated (or protected) from the natural world, we are starting to feel a number of issues caused by the lack of adventure, chalenge and even threat and danger in our lives. Which naturally brings us to,
3) Escapism - In a rigid society that wishes to bubble-wrap and control everything about anything and anybody (for our own good) it is only natural that people will feel the need to escape and kick like a mule against these imposed rules and regulations, different people find different ways, alcohol and/or drugs, gambling, shoplifting, you name it, somebody does it. Bushcraft offers the open and free back-country and territory that although in theory still under the control of people, feels pretty isolated and free with threat and risk absolutely in abundance as many of us have figured out (but that's exactly what we want).
So to summarise in a sentence,
"Bushcraft derives from the needs of the modern (early 20th to early 21st century) human who's lack of control over themselves and their lives, coupled with an ever-increasing overprotective, and ready-made, no efforts lifestyle and state of being has caused an internal conflict with the genetic code that has been programmed to the human kind for millennia and has therefore caused a romanticism of the great outdoors and a more primitive and self-sustained way of life."
Hope that makes sense