SOAP and REST at Amazon

From http://www.xml.com/pub/a/2003/12/09/xml2003amazon.html:

>The next issue was that of protocols. Should they support SOAP or XML over 
>HTTP (that is, REST)? In the end Amazon provided both and let developers 
>make the choice. Despite it being the "standard", only about 15% of Amazon 
>web services calls are made with SOAP, the remainder with REST.

Why do you think Amazon's users prefer REST?   Suppose every web service 
were available using either REST or SOAP - when would you choose to go with 
SOAP?

Jonathan