Writing content being looked at as mining is a great comparison. Another you could look at it as, is essentially a faucet! Except here, you get paid different amounts based on how much value people see in your "Captcha" (Comment. :P) and you don't just type random letter and number combinations in, with no real purpose.
The human readable addresses is definitely another major selling point. I can just tell someone my address, no need for a QR code, no need to copy/paste or carry a thumb drive with a text file, etc. I can just tell them "Send the steem to @lookplz, thanks." :)
All of your other points are valid as well, but these ones stand out the strongest for the common user.
Actually, that's not a bad idea for a company to build off of...
Imagine, something to validate humanity, similar to captcha. The company has a steem account (They wouldn't need one though, even, probably.) and they use the api to monitor the chain. The verification app shows the image as usual, the input it, it posts under the app id on the chain, the company's monitoring bot picks up that the correct information has been posted to the chain, they are verified human! :)