You know, it's just occurred to me that streamlining might not be entirely without purpose in space travel. After all, there's a lot of dust and micrometeoroids in space. Sure, you have the navigational deflector to handle that, but maybe the occasional speck might get through. And the smaller the forward surface area you present, the lower the probability of some stray piece of debris hitting your hull.
It could also serve a purpose in combat, in that a smaller forward profile would be a bit harder to detect by enemy radar/sensors and could have the same advantage against weaponry that it had against space debris (as long as you engage the enemy facing forward).