Realistically their does need to be some consideration but the medium they travel isn't air, but the occasional speck of dust, hydrogen atom, and other small stuff. It's not much but for interstellar travel there are still considerations needed, namely reducing your cross sectional area in the direction of travel. Long and thin gives you less drag since it hits less stuff.
Regardless the airplane looks doesn't make much sense anyway :)
Not a trekkie, do they ever land in atmosphere on these ships? You would want aerodynamics for that to reduce drag and thus heat, but I'm not familiar enough to know.
I guess they probably have good thermal protections with their future tech, though.
The ships can land and take off at least some of them can but they don't fly around in the atmosphere they just go up and down they're either on the ground or they're in space but they can't really manoeuvre.
Except for that one episode of Voyager where they just kind of forgot about that, but I think that was hand-waved away by saying that they just made the shields into a bubble and so essentially from the air's perspective the ship was a sphere. That's apparently what the shuttlecraft do too, which is why they fall like a brick whenever they're shot down.
I was thinking more about atmospheric entry and exit than flying around in the atmosphere itself... but a bubble would be weird because fast-moving spheres would create pretty unstable drag and induce spin, iirc.
They don't even need to fly nose-forward. The Enterprise could exit warp at any damn orientation it wanted. Blasting across the alpha quadrant nacelles-first, like Powdered Toast Man.
They actually do need to fly nose first, believe it or not! The warp bubble created by the nacelle has a front side and a back side. Essentially it bunches up space behind the ship and thins it out in front of the ship, turning space itself into a sort of wave that the ship surfs forward on.
This is what I remember from the TNG Tech Manual anyway