Relative simplicity versus absolute simplicity
We are the experts of our business and products. We understand our products complexity and are in the unique situations of seeing the full picture of all our design. Its important that we do not expect the same level of knowledge and insight from our customers and user.
We always aim for presenting the complex in a simple and approachable way. This is a key aspect of any successful design.
What we need to understand is the difference between absolute simplicity and relative simplicity. We often simplify something that was very complex to begin with thus making it more simple then it was before. This would be relative simplicity. The misleading thing about this is that the end product might still be complex, its just less complex then when we started. We should aim for making it absolute simple meaning that it is simple for someone seeing it for the first time not knowing how complex it once was. Basically making the most simple version of something that could possibly exist regardless of prerequisites.
Information in layers
An approach to making things simple without taking away the depth or control over the design is to layer information. Can secondary information be hidden by default and shown on click? Can we gather less relevant information into groups or sub-sections on other places of the product?
This requires a thorough understanding of what the main purpose of the product is and never stepping away from that purpose.
Give people the perception of simplicity, the first feeling should be I understand this. With a low threshold the chances are higher that our users too will become experts of our products.