First would be what size tank are we talking about? Are you going to have a solid platform for the tank to sit on like plywood, or just 2x4's or something along the edge?
I think you are going to get two answers to this. My opinion is no. Most commercial stands aren't going to have foam as the frames of the tank are plenty to support it as a whole. With foam on the bottom you can potentially add an up pressure as the tank settles onto the foam, it will crush on the sides but the bottom glass won't do that. Now you have pressure on that bottom glass pushing up and the water pushing down... not a good combo IMO
Your experience may vary, but why do that when most don't and never have a problem?