Yeah Chrome extensions turned out to be a surprisingly useful solution. I think we really need solutions that can be automated for clients with minimal hands-on afterwards. Hopefully we'll see more open up soon! Especially in the dashboard environment.
I'll try not to write a book haha. For the merchant, the checkout is the finish line. If we take care of any issues that may occur in the sales process (up to and including the cart) and then the customer trips over a hurdle right before the finish line, we all kind of lose the race. Abandoned carts are a thorn in the merchant's side and we can't prevent all of them. It's inevitable. We can only do our best to make sure we aren't the reason a customer chose not to convert to a sale.
So with the cart being the starting point, it stands to reason that checkout scripts are the next logical step to take in the direction of improving the platform and merchant success.
A few of the problems that I can raddle off at the moment:
Customers stacking discount codes.
Customers not getting their free shipping discount because they used a coupon code at checkout and it brought them under the threshold. A lot of these shipping, payment, discount and miscommunication issues all happen just outside of our reach.
This post about draft orders API shows another use case.
To put the potential uses in perspective, I was able to write a ruby script to solve some price level issues a Plus client was having the same day the cart scripts were made available. It was clean, very short time to deployment and the merchant will never have to bother with it. Not to mention scripts are much more portable.