Lattice topped pies do nothing more than to make a pie visually appealing. You can perform the same function of creating a vent within the pie with several slits cut into the top crust of pie, or using a pie bird. However, I’m a big fan of visually appealing food, and I think that some pies (i.e. cherry pies) require the extra effort to make them taste better. (kidding) (well, mostly kidding)