There were a bunch of considerations that went into armor choices from antiquity to the modern ages when gun powder finally made most armor obsolete.
The amount of padding that was required under any kind of heavy armor was formidable and when soaked in sweat significantly increased the overall encumbrance of the armor. Also the sun could turn metallic and laminate armor into an overheated oven very quickly.
Most heavy armor was worn by mounted soldiers who also had barding on their mounts and for the same reason, which was once the charge began they had little control over what they were exposed too in the fray that followed. Unlike foot soldiers they didn't have the moments to try to react to each attack but just had to bear them somehow. Foot soldiers didn't try to cut the legs out from under their mounts because dying under a ton of falling rolling armored horse wasn't a sound survival tactic.
The downsides of heavy armor were many but avoiding randomly dying in the fray was a powerful incentive. Until the pikes became a thing...
It wasn't until the decline of the
Pike and Shot era that you see a decline in the
Gendarme. Heavy cavalry and pike were discontinued although the use of light cavalry and bayonets would remain. The pike and shot formations could deter but not invalidate the use of heavy cavalry.
Volley fire had yet to become deadly enough. The end of pike and shot era saw some interesting innovations: in the 30 years war Swedish King Gustav Adolphus broke Tilly's cavalry charges by interspersing musket units between his cavalry units to use volley fire to break the enemy charge, and then enable him to counter charge. You did see early use of trenches though and they were very successful. I can't remember the battle off hand but I belief a Spanish pike and shot infantry unit broke a French charge this way in the mid 1500s.
