How about in your examples, the ships are designed by different species, with different histories and influences, so while the general idea is similar, the results vary a bit.
For your EARTH examples (subs, destroyers, planes), pretty obviously all built by the same species, same knowledge of history of warfare, and same general technology behind the different factions' designs?
Pretty easy to explain the design differences that way, isn't it?
But yeah, it's mostly so you can make them iconic and represent them on screen and have people just KNOW who's who. Wouldn't it be kinda lame if the Klingons and Romulans were all flying around in essentially replicas of the Enterprise, but just changed the font on the hull, or the shade of blue in the nacelles?
Same reason that most species all seem to be wearing the 'team uniform' whenever they are shown, in just about any sci-fi series. Easy way to distinguish them from each other, allows you to try and set the tone for them, flesh them out a little more than having the entire cast standing around wearing jeans and t-shirts. In basketball, you should know which guys are on your team, and can tell if you look, but they make them wear different colored jerseys anyway....
For your EARTH examples (subs, destroyers, planes), pretty obviously all built by the same species, same knowledge of history of warfare, and same general technology behind the different factions' designs?
Pretty easy to explain the design differences that way, isn't it?
But yeah, it's mostly so you can make them iconic and represent them on screen and have people just KNOW who's who. Wouldn't it be kinda lame if the Klingons and Romulans were all flying around in essentially replicas of the Enterprise, but just changed the font on the hull, or the shade of blue in the nacelles?
Same reason that most species all seem to be wearing the 'team uniform' whenever they are shown, in just about any sci-fi series. Easy way to distinguish them from each other, allows you to try and set the tone for them, flesh them out a little more than having the entire cast standing around wearing jeans and t-shirts. In basketball, you should know which guys are on your team, and can tell if you look, but they make them wear different colored jerseys anyway....