Because I'm an independent translator, you will have direct contact with me, so you can be confident that I have received and understood your instructions about style, format, and content.
Another important consideration for many translation users is direct contact with the translator. Being able to communicate directly ensures that the translator receives instructions about style, format, and content directly from you. It also ensures that a translator, if confronted with an extremely technical text or if unsure of an appropriate rendering, can ask you for pertinent background or for a brief description of new technologies.
Obviously you will have direct contact to independent or in-house translators. Some agencies permit you to speak directly with their translators; some do not.
If translators and users are not in direct contact, the translator often has to muddle through difficult, technical text without having access to the substantive expert, you.
Likewise, without direct contact, your instructions may not get through all the administrative layers between you and the translator.