I don't think starfleet would bother to rebuild doors for bigger ships in TNG (maybe one or two), these bases had 4 doors, I always thought that each doors were fited to adequate size like : the smallest doors for ships like oberth, medium doors for ships like constitution or excelsiors, large doors for ships like akira, nebula or even ambassadors and the biggest doors for ships like galaxy, sovereign (tho this one would fit through large doors) and excalibur, such use of doors would be logical as they wouldn't have to rebuild them for bigger ships than before (ambassador -> galaxy -> excalibur)