I think, for the sake of balance, we should say plate is super heavy and restrictive. Of course, back then sheet metal was hyper expensive, but suprisingly mobile. William the Conker could somersault onto his horse in full armour, for example.
One idea is half-plate. Not as expensive, not as heavy, but not as protective.
But the last thing I want is to be stuck in a swordfight with some nob whose as agile and evasive in full armour as I am in a shirt and funny hat. Witchunters don't wear much physical armour, you know.
EDIT: I know the problem! Plate armour is fine, but because it was so expensive, in the 15th centurt people began to make "Munition" armour, which was cheap and protective, but bulky, unwieldly and heavy.
There needs to a distinction between "normal" plate armour and "munition" plate armour.