From SPARQL Working Group
The Working Group has considered your comments about allowing FROM and FROM NAMED clauses after the SERVICE clause but we've opted for the current design for simplicity and due to a lack of implementation experience. Along these lines, the group will investigate more about how datasets will/can interact with the new federated query form as the community gets more implementation experience. Based on this, a future SPARQL-WG will be able to consider your comments in more depth. Unfortuantely, the Working Group has very tight deadlines and there is not much time left to design and implement substantive changes to the specification now.
We would be grateful if you would acknowledge that your comment has been answered by sending a reply to this mailing list.
Carlos, on behalf of the SPARQL WG