Off the top of my head 1) No landing legs so they save the weight that can be used to improve the performance of the rocket 2) No landing legs also means they can save time between refurbishment since they don’t have to go through the whole folding the legs back into position. 3) Landing directly on the pad saves the transportation time and cost of the booster and ship, simplifying logistics 4) In an ideal scenario, they can catch the booster, put it back on the pad using the same chopsticks, stack a starship on top and go again, minimizing time between reflights 5) Simplifying hardware as they need to build the catching mechanism once for each tower and not legs on each rocket and also potentially reducing damage since they catch it higher up