I think all smart contracts (i will call them that) are important, whether it's ideas like the one you described, or the much talked about idea of an open bazar style app, where users would be able to trade goods via steemit using SD, without having to make a "sale" post.
It would have to be build in of course.

Then, of course, things like a trading platform on top of steem, whereby using the SD peg, users will be able to buy other currencies from within their wallet, so basically to make it more of a bank account (the wallet), with different options.

The reasons I'm opting for such smart contracts first is so that we can give steemit a more liquid "kick" and encourage a bigger building up