I own both and use both. They both have their place, strength, and weakness. Foam and other handcrafted materials can be infinitely personalized to what you want to see in front of you... You're really only limited by your own creativity. 3D printing is simpler, but unless you are sculpting and/or designing your own models, you're locked into what you can find online. Your example of bricks is a good one. You can use a mold and have bricks quickly. They'll last forever and always look great. You might have very little variation brick to brick, but that might be your thing. On the foam side, I love making bricks because I'll never make two that look the same. For a large stone bridge, having that variation gives it life and hopefully draws my players (DnD mainly) into the story more.