>>64211754 (OP)
Steel armor is heavier for the level of ballistic protection it provides (against certain threat profiles) than aluminum and polymers/composites.
Also, metal armor would get a fairer shake if they actually implemented features to reduce or prevent fatal spalling injury, like composite liners and flared rims around plates to catch spalling. FFS the latter was well known historically and a nearly universal feature on medieval-early modern plate armor, yet the concepts we see get shilled nowadays look like they're deliberately designed to send shrapnel into your arms and neck.