Ever get looped into an e-mail thread on the fifth round and tried to figure out which part you're supposed to read? All you see is a tangle of text chunks indented with strange characters and punctuated with outdated header information and worthless "Thanks!" replies.
Whether you know it or not, when you compose an e-mail, you're designing. When you reply to an e-mail, you're designing.
When you assemble a grant proposal, a business plan, an executive summary, you're designing.
And good design gives you an edge. How big an edge? It's the difference between getting read or getting ignored. You don't have to understand Photoshop or other design programs to be able to create clean business communications. You just have to develop an eye for the difference between visual order and visual noise.