I came to roughly the same conclusion from the emails I received from my "How to Hire Me" post. People make all of the mistakes there that they make with online dating. From an abstract point of view it is the exact same problem.
When I have an OKC account, my strategy is just to write the first half-funny sentence or two that come to mind, shoot off the message, and move on.
Even when I apply for jobs and write a cover letter, what do I do? A dating site message with a funny accent.
Dear Companyboss,
I write in reply to your advertisement of <date> in the Foobar Herald.
I am <skills/titles>. While working at <previous employer>
I used <technology/skills>.
I have included my CV and I look forward to your reply.
Yours &c &c
Writing short messages isn't because the writers are lazy. It's a rational strategy that maximises coverage and minimises the emotional cost of being rejected after making a large investment.