Since the point won't be sticking out when you put your wheel on (duh).
Since it shaves off a lot of back-end weight.
Since having the regular drop-out style that a TSI has is an ankle magnet and even on the old frame-style decks most people preferred fastback deck plates to square backs.
Since the original TSI Freestyler was a huge success.
i dont see why people care about the drop outs if you dont put your feet there (unless your riding ski) but like it will take off some weight at the back where you dont need big dropouts.