Honestly, because it caught on. Its as simple as that.
Guys grossly exaggerated how amazingly fantastical super duper amazing uber mega better the flavor was, threw in a few words like organic, then a few negative words about the normal stuff like pesticide and chemical then the giant circle jerk of people convincing each other its the greatest thing since sliced bread got rolling...
...perception...
...placebo effect....
...take your pick.
At this point in time, there's absolutely nothing proving one type of wick safer or healthier than any other. Anyone proclaiming one is safer than the other is talking out their rear. (damned word filters)
Yep, which is why I would like to see actual scientists take these wicks into a lab and run the vaper through a GC-MS.
I am personally not sold that cotton is the best wicking material. For one, it's burn temperature is low. This isn't usually a problem, but I am sure we all are inhaling some burnt cotton. And, two, raw cotton is a known health hazard (that's why they treat it) and cotton mill workers have to protect themselves or risk contracting byssinosis (lung disease). Now, it's doubtful we are inhaling lots of loose cotton fibers since the wick is saturated but it is something that makes me wonder about the safety.
In a way, I worry more about organic cotton than I do bleached. Organic cotton hasn't been treated (at least not the way regular cotton is) and is therefore subject to potential bacterial contamination. Cotton is a plant and gram negative bacteria naturally grows inside it. This is why only sterile cotton is used for medical purposes. I have vaped sterile cotton and I get a weird taste (probably from it's treatment), so that's a non-starter for me. Also, some people have reported allergic reactions when vaping on cotton, which means that something from the cotton is being transferred into the vapor (I think we all knew that anyway).
I think the industry should look into some synthetic materials with very high heat tolerances (ceramics, etc.). Ekowool looks good, but I haven't tried it. There are various mineral wools out there as well (though I have no idea how it would work in an e-cig).