Lots of reasons.  Here's a few:

1.  It's currency agnostic
2.  It eliminates central clearing houses and centralized exchanges
3.  It federates payment networks (SMTP for money)

Overall, I just think Ripple makes sense and allows access to monetary freedom, for more people, while still allowing them to use their existing things of value.  Remittences for example, is a big reason I like Ripple.  I'm also a big merchant guy so, understanding merchants would prefer to make one integration and allow their customers to pay in any currency, while still receiving just USD, is huge.  That replaces the need for merchant accounts for credit cards, then a separate integration for each cryptocurrency you want to accept.  It's just common sense innovation, IMO.