Convenience Checks

I was opening up some mail, and I saw that the bank I have a Visa through sent me some "convenience checks." They said it was a "congratulations" for paying off my Visa.

What is so convenient about these checks? What is it about them that congratulate me?

The facts:
- the checks charge to my credit card as a cash advance (instead of a regular charge)
- the interest is 28.99% (compared to the typical 16.99%)
- interest is charged from the date of posting (whereas I normally have a 31 day grace period)

I'm so glad I know these facts so that I'm not "tempted" to use these anywhere. They are going in the shredder where they belong, I'm entirely too proud of my $0 balance!