You can't think of any negatives? I don't think that you are thinking very hard about it. Its complete quackery.
The "life force energy" or Qi, does not exist and is not recognized by medical science, or any other science for that matter. So clearly the idea of blockages in your energy is drivel.
The two biggest negatives I can think of are; you pay big money for a placebo and foot massage, and people may be trying to treat potentially serious illnesses with something that has no proven efficacy, which could delay the seeking of appropriate medical treatment.
Edit:
~G~, It's not a matter of nay sayers being closed off to energy, no one can show this "energy" exists, in fact the word energy itself is being misused. Energy in attribute of something, a measurement of work capability.
So what is the physiological mechanism that causes reflexology to "stimulate the womb" and what does that even mean? How exactly does it bring on early labor? How do you "send blood flow" to specific internal organs? Isn't the blood already flowing there anyway? How do you exactly manipulate this "energy"? What you're saying makes no physiological sense, as far as I can see. Are there any independent clinical trials that support what you claim?