What are the fundemental disadvantages to traditional rocket designs, such as the Ares (1 and 5), Saturn 5, Delta series, etc? So far I've come up with incompatibilities with existing airport infrastructure and a partial or total lack of reusibility (what parts are reusable need to be fished out of the ocean). Especially in comparison to something like the skylon or some other advanced spaceplane, can anyone think of other disadvantages, or just disadvantages in general? I'm not very knowledgable in this subject. Thanks.