Don't forget that with Vital Strike, you are only doing one attack, but it is at your highest bonus. The attack you are "missing" is one that would be at -5 to hit compared to the first attack. So while you might not be doing as much damage as a Full Attack *if* both of those attacks hit, you are making sure that the attack with the best chance to hit is doing some extra damage.
I would generally still prefer to be able to make two or more rolls to hit, in any case, but it's something to consider. . .