Why aren't you (really) good at graphic design?
Ten years ago, you had a wide range of excuses for being a lousy visuals person. Starting with no talent, leading to no skill and going from there.
But now, in a world where it is expected that professionals will be able to make beautiful powerpoint slides, handsome business cards, clever bio photos and a decent website, it's as important as driving. And easier to learn and do, and requiring less talent.
No, you and I will never be gifted designers or breakthrough designers. But there's really no reason not to be really good.
I put together a page with some blogs, books and sites you can check out. An hour a day for a month and you won't have to hide your face in shame. Sure, hire the very best in the world when you need a breakthrough. But you don't have to pay for better-than-mediocre design. You can do it yourself.
(Update: as expected, I heard from a few designers, upset that I would recommend that anyone do pretty good design. The thing is, as a designer, if all you can offer is a time-saving way to get pretty good design, that's a tough row to hoe. The magic for the great designer is that once someone understands how to see, understands how powerful great design can be... they are going to be the first person who wants to hire you.
The fact is, business people do copywriting, simple legal and accounting work and more, on their own, every day. You compose your own email, don't you? If your legal decisions were as bad as your design, you'd get fired in a minute for libeling people. Getting pretty good at things is merely a first step, but one that you need to take in order to be ready to spend the money to get great.)