B&M's giga coaster brake runs are designed to be tall for the same reason that Intamin trains standardized over the shoulder restraints up until recently: rider comfort. Almost every modern ride uses magnetic brakes, and those brakes operate by a principle known as eddy currents. The key factor of eddy currents that drive both Intamin and B&M designs is that the force generated from the induced current is proportional to the input velocity - the faster the train hits the brake run, the harder it will stop. To make these physics relatable, remember your last ride on Top Thrill Dragster or Xcelerator. If your memory serves correctly, you'll remember your torso getting thrown forward fairly violently. To mitigate this, Intamin started putting their over the shoulder restraints on all of their rides as the straps catch your shoulders and torso and keep your body in a more comfortable position. B&M gigas simply solve the same problem in a different way. Instead of slamming into the brakes at 75mph and having your upper body roll over the clamshell restraint, B&M simply adds elevation to remove a ton of kinetic energy before gently slowing the train to a crawl. B&M's solution may cost slightly more in materials (taller supports) and look goofy to every enthusiast, but it allows them to maintain their high quality riding experience and rider comfort with the clamshell restraint, and probably helps with sequencing the trains on that long slope down to the station.