XRP functions as a transaction stamp and temporary holding/conversion currency. It's value is expected to rise as the network grows and becomes more useful. Ripple's alleged "premine" makes sense when you view XRP like a stock that is gradually issued as the company grows.
RESISTANCE IS FUTILE, JOIN RIPPLE OR BE ASSIMILATED!
I agree with the "premine" part, it makes sense because it's a distribution like a stock.
But you said "is expected to grow", to fulfill its function it doesn't necessarily need a ridiculously high marketcap.
Also, In a recent interview chief cryptographer David Schwartz said that it's technically possible for the USD itself (or another major fiat currency) to be used as a bridge currency as opposed to XRP

I'm not bashing XRP (lol I hold some myself), I'm just saying I am not 100% convinced on it and I'm trying to be objective (on the other hand, I'm pretty convinced about the usefulness of the ripple network as a distributed ledger system, which I think is better than the bitcoin blockchain).