Nor is there any spiritual reason for it to exist any more.
ALL the things built by Moses were shadows of, and patterned upon, the REAL items in Heaven.
The exception was the Tabernacle, which was a temporary, portable structure for use until the earthly Temple would be built at the designated place; that Temple itself was a shadow of the Heavenly Temple.
Jesus, having nailed the blood ordinances to the Cross with His sacrifice; and having rent the veil of the Holy of Holies, has made obsolete all of the Temple furniture (and, indeed, the Temple itself: "in three days, I will rebuild...": He is our temple.) related to sacrifices, or the need for an intermediary (earthly High Priest) to approach the Mercy Seat on our behalf. He is now our High Priest, and all can openly approach Him.
Like the brazen snake on the staff that Moses was instructed to make in the wilderness later did, there is every danger that the Ark and other artifacts would become objects of idolatry, being worshiped in their own right. Indeed, we see much of that mind set already, even though the Ark has no verifiable physical existence; and to a lesser extent, we also see it in the Shroud of Turin.
God hates idolatry, and I have no doubt that he would have long since removed these items as the potential stumbling blocks that they are.
The real Ark is in Heaven, in the real Temple.
Changing "every danger" to "a virtual certainty" expresses it, I suggest, more accurately. But I don't presume to correct you, for your entire post was beautifully constructed and expressed. Thanks.