to get the best handling out of your car you should get them however it is not necessary

 

My caster/camber platesare set all they way outward in order to get the front end into alignment with my 2"drop. It still isn't 100 % right on, but really close... I can't see why not get them as they are only 250 dollars (or less) and if your wheels are out of caster/camber adjustment, you're going to suffer with less stopping ability and lose grip in the turns.... Then again, you can get them later if you find out that you need them. They can be installed later...