There is not much hard scinece behind those findings. It's impossible to take two groups of 1000 men, isolate them in a controlled environment, and repeatedly expose them to the virus to see who is infected more often. Even if such a study was done, it would be subject the random nature of the virus and individual immune responses.
The "skin" theory goes against the science that HIV penetrates exposed mucous membrane much more easily than it does skin. If there is a difference, it would be more likely that an uncircumcized penis is slightly more prone to minor injuries than a circumcised one, especially if other conditions are already present.
The historic trend has shown a greater correlation between infection trends and high risk behaviours, with the "penis issue" being more of a coincidence than a factor.
The first outbrakes were in Central Africa - where there are both circumcised and uncircumcised ethnic groups.
The next area HIV spread to was the North American gay male population, where HIV infected mostly circumcised men until safer sex practices took hold.
Then, in the late 80's & early 90's sextourism and the local sex trade created the next explosin in Thailand, Cambodia an Burma - where the majority of men a are not circumcised. It is also there that the virus mutated a more infectious strain.
The new areas of HIV infection growth will be India, China, and Russia - well over half the World's population and far behind on AIDS awareness and safety - as these populations are overwhelmingly uncircumcised, it's reasonable to assume that uncircumcised men will be highly represented in the new infection trend.
Until these regions, as well as Africa, adopt safer practices closer to those in North America & Europe, their infection rates will be much higher, probably die to behaviour factors.
Most men in Eastern Europe & India don't believe in HIV transmission through Heterosexual intercourse. They think it's a myth of Western political correctness that was adopted to protect homosexuals from being singled out.
A few years ago, a documentarist approached three middle aged men in a Ukranian industrial town on the way out from a known brothel. He asked if they used condoms - they shrugged and said "No". Asked if they were worried about HIV, the men laughed and said "What for, none of us are gay?".
