The basic difference between a developer and a consultant is, the consultant knows about the business and the marketing part beside from just the development thing.
They are the ones who will understand what software will work and which one not, how to run the software, that works decently to a great one.
With the software consultants you get to understand the people and not only the software development. With a SaaS based company you need a software consultants. They can understand and convince the clients on how the service works and how it will benefit.