Well, there are several distinctions, but an important one is that the Glove just hasn't been around long enough for the dangers of Glove abuse to become apparent. If it turns out that excessive Glove use raises your risk of concussion, or ages your joints prematurely, or induces heart attacks in 2% of the population, or causes impotence, or takes twenty years off your life, or whatever, there might come a day where nobody sees a distinction between Gloves and performance-enhancing drugs.

(Not that I have any reason to expect any bad side effects. But you never know. It takes time and statistics to work these things out. Physiology is holistic. And, when you remove one bottleneck (in this case, the rate at which your body can dissipate heat) you inevitably run up against another bottleneck, one which may have much scarier consequences than the first.)