If we look at orbial mechanics, we can find great tables like these, demonstrating the name of the periapsis and apoapsis around various celestial bodies:

Objects     Periapsis       Apoapsis
         
Galaxy      Perigalacticon  Apogalacticon
Black hole  Perimélasma     Apomelasma
Star        Periastron      Apoastron
Sun         Perihelion      Aphelion
Mercury     Perihermion     Apohermion
Venus       Pericytherion   Apocytherion
Earth       Perigée         Apogee
Moon        Periselene      Aposelene
Mars        Periareion      Apoareion
Jupiter     Perizene        Apozene
Saturn      Perikrone       Apokrone
Uranus      Periuranion     Apouranion
Neptune     Periposeidion   Apoposeidion 
Pluto       Perihadion      Apohadion

My question is why? Why have so such composite names? Are there a few standard justifications for why such naming is useful?

I ask my question from a linguistic perspective. Obviously the real reason why it is done this way is because this is the way it is done. However, often in linguistics, we can come up with "reasons" for why things are done. For example, in mountain climbing, we see vocal calls between two climbers like "on belay" "climbing" "climb." One of the justifications for these terms is that they have different numbers of syllables: 3-2-1. Obviously it is very bad news if, in bad windy conditions, you mistake one instruction for another, and it may be that the number of syllables you hear is all the information you get! We see similar in the military, where language forms patterns that can withstand the din of combat.

Is there a reasonably accepted justification (or a few common justifications) for why we have so many terms for the periapsis and apoapsis? Or is it just the way it is done?

If we look at orbital mechanics, we can find great tables like these, demonstrating the name of the periapsis and apoapsis around various celestial bodies:

Objects     Periapsis       Apoapsis
         
Galaxy      Perigalacticon  Apogalacticon
Black hole  Perimélasma     Apomelasma
Star        Periastron      Apoastron
Sun         Perihelion      Aphelion
Mercury     Perihermion     Apohermion
Venus       Pericytherion   Apocytherion
Earth       Perigée         Apogee
Moon        Periselene      Aposelene
Mars        Periareion      Apoareion
Jupiter     Perizene        Apozene
Saturn      Perikrone       Apokrone
Uranus      Periuranion     Apouranion
Neptune     Periposeidion   Apoposeidion 
Pluto       Perihadion      Apohadion

(table from How do apsides of celestial bodies get their names?)

My question is why? Why have so many composite names? Are there a few standard justifications for why such naming is useful?

I ask my question from a linguistic perspective. Obviously the real reason why it is done this way is because this is the way it is done. However, often in linguistics, we can come up with "reasons" for why things are done. For example, in mountain climbing, we see vocal calls between two climbers like "on belay" "climbing" "climb." One of the justifications for these terms is that they have different numbers of syllables: 3-2-1. Obviously it is very bad news if, in bad windy conditions, you mistake one instruction for another, and it may be that the number of syllables you hear is all the information you get! We see similar in the military, where language forms patterns that can withstand the din of combat.

Is there a reasonably accepted justification (or a few common justifications) for why we have so many terms for the periapsis and apoapsis? Or is it just the way it is done?