This comes from a post I did on the HowDesign Forum:
There are three MAJOR benefits that a company gains when bringing in full time designers, and has happened in my organization.
More Active Commnication
Communication is more active when the designer is there in the initial meetings of a marketing campaign. Usually the company would go to the studio and say that “We decided to do a website and promote it through some emails.” The studios would comply and deliver the work. Having myself in the initial meetings helped to push what they were really looking for in the first place, and I was offering solutions that actually fit their vision, which is often lacked when using outside designers. Sometimes I couldn’t handle all the work and would have to use outside agencies, but with a clearing understanding of what the final approach, concept, and deliverable would be.
More Intimate with Business Models
In-house designers become more intimate with the business than the outside designers could ever be. When first meeting with groups about their campaigns, I would ask for all the marketing materials that they have ever produced in the past to get a better understanding of the clients/target audience and would followup with questions about their business before ever jumping into a design or idea. This is somewhat of a surprise to almost all of them, but leaves them with a feeling that I have become part of their team and not just someone executing their ideas. In fact, do a creative brief on a project to really surprise them. They’ve soon learned to come to me before starting any project so that I can offer them the best ideas and solutions to fit their message.
More Money for the Business
Lastly, time and money, the biggest selling points. Outside companies are charging prices that include overhead, lunches, phone calls, every single edit, the list goes on. Example: A team in my company got a quote to do a website for a large event from an agency for $20,000 that would include about 5 or 6 pages. I produced the site in about 5 days that included every feature they requested from the agency. I then went above and beyond their discussion and added in printable presentations and streaming videos and audio from the event as a followup to those that attended. And we produced it at a fraction of the cost.

I'm Brad Cooper, a user experience designer and front-end programmer with a passion for actualizing visions. I strive to create a piece of art in each site that I put together both visually and technically.