There has been lots of discussion about the "wild hoof" on UKNHCP. Its too long to go into here, but if you are interested you can find it at http://uknhcp.myfastforum.org/about1451.html
Personally, having seen desert hooves, mustang hooves and lots of UK hooves, the one thing I am pretty sure of is that hooves are brilliant at adapting to the surfaces and environment they live and work on. In the UK, that means a warm, wet climate and work on a huge variety of surfaces.
Its something we've talked about in "Feet First" as well, but basically hooves like to load centrally, if possible, and to land heel first, if possible, no matter where they live.
They aren't always allowed to do that, of course, but if you work a horse barefoot in the UK consistently, and let their hooves follow these 2 golden rules, you will tend to have a healthy hoof with a wide, strong frog which has an active weight-bearing role on hard ground such as roads.
Even so, the same hoof, on the same horse, doing the same work can look very different if the climatic conditions change - the 2 photos are of Felix' hoof, the top during a dry spell and the bottom during a wet summer. His work levels and environment were the same in all other respects. Interesting, huh?! :-)