If they are just base tickets, then there is no advantage to getting them in advance. Disney offers no discount for the advance purchase of base tickets. But, if you're adding hopping, waterpark fun & more or both, there are some small discounts associated with making the purchase in advance.
For instance, the gate price of an adult 8-day hopper is $261.99. The advance-purchase price is $253.47. You'll save about $8.50 per ticket by buying them in advance rather than buying a 1-day pass and upgrading it later.