Seversky, Kartvelli and Republic designed their airplanes from the skin in. Back during the 1930s, engineers determined that symmetrical teardrops created the least drag. The Granville Brothers's series of Gee Bee racers are perfect examples of airplanes based upon teardrops that are three times longer than they are wide.
Seversky and friends started with the most streamlined teardrop and drew airplanes inside those teardrops. The simplest way to define fuselage top and bottom profiles was to rotate that teardrop around the crankshaft. Then they added canopies, fins, wings, etc. outside the teardrop.
Republic's P-47 thunderbolt only had egg-shaped bulkheads to accommodate the massive supercharger and all its plumbing. P-47 superchargers are mounted underneath the aft fuselage. That deep fuselage also helps streamline wing roots, eliminating the need for complex, curved fillets (e.g. Spitfire). Teardrops are easier to streamline if wings meet the fuselage near the equator.
When Republic started building jet fighters (e.g. F-84) they continued drawing teardrop fuselages, just lengthening them to accommodate faster flight ( still sub-sonic).
OTOH A-10 is ugly because it was designed from the armament outwards. Republic A-10 Thunderbolt 2 (aka. Warthog) is ugly because it is designed for an ugly job: killing the massive waves of Soviet tanks expected to invade NATO during the Cold War. Tanks ae ugly and covered in armour so thick that few aerial weapons can kill them. Therefor A-10s' primary weapon is a huge, 30 mm cannon.Its six barrels allow dumping the maximum number of bullets in the few seconds that an A-10 can see its tank targets hiding under trees, hills, cammoflage nets, etc. All the other airplane components are wrapped around that massive Gatling Gun. The A-10 cockpit is high and well forward to give the pilot the best possible view when turning in tight valleys. Even the nose wheel is off-set to keep the massive cannon on the centre line. A-10 engines are mounted above wings to reduce the risk of sucking in gravel when flying from rough airstrips. Engines are mounted wide to reduce the risk of a failed engine killing its partner with shrapnel. Twin tails serve two functions. First, they operate in clean air, away from muzzle blast, etc. Secondly, Republic hopes that A-10s can fly home with one tail shot off. Finally, A-10s are not half as pretty as supersonic fighters because they don't need to fly half as fast. As long as A-10s fly faster than tanks, they are fast enough to do the job.
Even the modern Russian Su-25 Frogfoot tank-killer is only pretty from a distance. The greatest aesthetic difference is its shoulder-mounted wings with engines in the "arm-pits." Those low-mounted engines are easier to service, but also easier to kill with AAA. Up close, Frogfeet (sp?) have lumps and bumps, angular lines and flat canopy panels like attack helicopters. Attack helicopters are the ugliest helicopters ever made!
Northrup's tank-killing competitor (AX program) was only marginally prettier than SU-25 or A-10 but would have added lumps and bumps and antennas by the time it entered service.
When North American designed the B-25 Mitchell bomber and P-51 fighter, they learned that it was easy to streamline wing roots as long as they met a slab-sided (square) fuselage at right angles. IOW only included angles less than 90 degrees need complex curved fairings to streamline airflow and reduce interference drag. Slab-sided fuselages are easier to manufacture.
Big noses on F-111, F-14, F-16, etc. are defined by the diameter of the radar antenna.
