That's a good point. But then why didn't the Planet of the Titans ship go after them? Or maybe the other ships' captains just assumed the Excelsior would catch them, and didn't bother?
Remember the destination, too. Genesis was "planet forbidden" and they might not have wanted any other ships going there due to the political situation. At least not until they can detail the right
Captain and crew. And by the time they get there, the BoP is already en route to Vulcan and the planet/system is falling apart.
Great design, though. I would think the exterior hatches are ingress/egress, though beaming into the area behind the cockpit could be possible. Entrance to the cockpit itself would be from the inside and just lacked that appropriate detail (though it could arguably be armored/pressurized and not look like an overt conventional door/hatch.