I think a broad professional experience is mandatory to be a successful Enterprise Architect (EA). The business experience gives context to the use of IT technologies for solving real life business and maintains 'IT' as the enabler.

A good understanding and experience of the major IT Technologies is also a must to be successful; in the same manner a good cabinetry maker understands his tools and materials. The EA is expected to be fully conversant with the available resources from which to construct the most appropriate solution for the business.

By having the ability to view and understand the underlying business issues confronting the enterprise, the EA can formulate an appropriate solution from their available materials (IT Technologies & Processes). Additionaly the ability to understand and converse with the business units in "their language" is the only way an EA can gain thier trust & respect.