While both graphic design agencies and freelancers have their pros and cons, hiring an agency is sold with some very distinct advantages.
The combined connection with an agency is just a big advantage for a consumer as graphic design agencies may have teams of staff looking after a job, this means that there won’t be any threat of sick staff postponing a deadline. Agencies will even do have more experience than freelancers in coping with large clients and accounts and will usually have an extended listing of satisfied clients. Another big benefit of an agency is that for their size, the agency teams can develop a broader range of ideas than the usual single freelancer can. A design agency may have access to higher resources then the freelancer with more extensive industry contacts and better equipment. Brochure Design
The real benefit of hiring an agency is that you generally know what you’re going to have, while freelancers are more unpredictable. I don’t speak for many freelancers however in my experience almost all are after big chucks of money and often don’t look at the client’s needs to exactly the same level as an agency.
Graphic design agencies hire accounts people to manage clients and manage expectations while a freelancer is more than probably be a developer in your mind and are often not good at building client relations. This can result in missed deadlines and unreliable work ethic. I don’t speak for many freelancers needless to say but there can be without doubt that agencies are better organised.