The EU Commission is built up as the French central administration is, in a very hierarchical structure where civil servants are only allowed to talk with their next-in-command.
The lower levels are not allowed to make decisions, but must rely on orders from above.
Letters are answered via long chains of command and follow the advice in the written Commission manual: "L'Expression écrite dans les services de la Commission des Communautés européennes”.
Notes
Once, Romano Prodi received a note with 10 signatures and asked: Who of them have actually read the note? As this demonstrates, when everybody is equally responsible no one takes the responsibility.