D&D 5E (2024) So the Armorer still need be Wearing before Don his armor.

[pukunui]

I think the intent is clear, even if the wording is off. Once it is arcane armour you can don/doff as it as an action.

I think the only benefit that really needs to be "while wearing the armor only" is the spellcasting focus one. You shouldn't be able to use your armor as a focus if it's sitting in a heap out of reach. Also, the "no Strength requirement" benefit only comes into play while you're wearing it. It's irrelevant when you're not. So yeah, the wording is poor, but the intent is clear.