“The builders of the Ark of the Covenant had never seen angels; they went by a description and what they knew as craftsmen.”
Don’t forget that they were commanded to do so.
Monstronces are made in supply factories to appear as something they are not and were not commanded to be.
A Host is delicate and fragile. He, that is, Jesus in the Blessed Sacrament, requires something to safely hold Him. Does He not then deserve the best we are capable of giving Him? We adore Him, not the monstrance! Not all monstrances come off an assembly line, either. Some are fashioned by the world's finest craftsmen- a labor of love. The Host needs something to protect Him. What would you suggest? Do you not believe in the Real Presence? If you don't, then why does it matter to you how we honor Jesus? If you don't believe, then you don't know how much Jesus in the Blessed Sacrament can mean to a true Catholic. When He is exposed and placed in that monstrance, it is a sign for us to kneel and adore Him, not the vessel in which He is contained and protected.