My point is that I would be flying around on my main and be using two gathering professions as my "active" professions. Where normally, I would not even have this available. Every person would be flying around with their gathering professions as active. There is already enough complaints on the forums about botters, and a low re-spawn rate on herbs/ore.
Additionally, most people level an alt for fun, and just use it as a "gathering alt" in addition. I'm not sure how many people think "darn, I'm JC/BSing and now I HAVE to level up another toon just to get mining! Oh woe is me."