Enterprise Architect is a business man meaning should understand the cost implications involved in running software enterprises end to end. He should be able to wear a BA’s hat when required translating requirements and clearing road blocks which are found at the business/IT intersections. He should be well versed with all forms of business analysis and be able to separate the grain from the husk. So an EA can be someone who progressed from a BA to an EA or became an EA via other routes. At the core of an EA’s skill set is someone who knows the business of running an application / product or an Enterprise using IT. If you look at how EA has evolved over the years from being a core technical person to someone who bridges the gap between business and IT.
Most EA are accountable for couple of million in the Project/Product’s outcome. So although good techies can take a product/project to a level it needs business focus to be able to focus on the results of the business outcomes. You can develop a great product using technology but the point of inflection where it meets end user needs and the market can be well understood if the business needs are well understood.
An interesting technology creation is twitter which enabled to let people talk publicly about their cats and dogs. Initially it was thought to be an useless creation having no immediate business value but it has as its core of connecting people at a scale unimaginable in history. The 140 chars is the new low and high as well.
EA should know the business side well …among other things