Branches have a natural process of lowering or "drooping" with added growth weight. Suggested every 3-5 years removing certain branches allow trees to grow healthier & less chance of snapping limbs.
Cleaning & Thinning the interior trunk/limbs removes the unneeded clutter within the tree, and is visually appealing when done.
Smaller limbs, known as "Suckers" or Water Sprouts will form along the main trunk. If not addressed, these can cause harm to the tree, commonly growing into the mature limbs & leeching moisture from the areas where the tree needs it most.