Occasionally we don't seem to know what is good for us. We are very often too stupid to break out of our ignorance and find a better way.
Many nations in the world have coin denominations that are a bit larger than the smallest of change. In Switzerland, for example, I remember the convenience of a one, two and five franc coin. They were all silver in color, but different in size and with a different imprint, of course. No one seemed to have much difficulty figuring it all out. The coins were durable, efficient, convenient and ubiquitous.
Once upon a time in America we had the silver dollar. I recall during my first visit to Las Vegas, half a century ago, that the casinos did not have a $1.00 chip. They used the real deal. I will admit, however, that walking away from a crap table with a hundred of them was a bit of a load. Fortunately it didn't happen that often.
Overnight, the cartwheels disappeared. A decade later the Susan B. Anthony dollar coin surfaced. It was slightly larger than a quarter and for those dimensionally challenged individuals, it had a raised polygonal edging to allow a tactile differentiation. That was inadequate for the terminally dumb. People eschewed the coins claiming inability to tell the difference.
Despite that, the logic of a dollar coin remained. The futility of trying to stuff a wrinkled silver certificate of George Washington into the obstinate mouth of a vending machine didn't seem to bother folks enough to make them accept the gold-colored Sacagawea dollar.
Now, we've got this:
Billion Bucks in Presidential Coins Lies Dormant
There simply is no good reason for not putting those coins into circulation. They might be used and that would be fine. They might be rat-holed by Grandmothers to save as a legacy for their grandchildren. That would be equally fine. If they were released at the same time as a discontinuation or drastic reduction in printing of the one dollar certificate, they would have to be accepted and maybe even the ignorant might come around to the convenience.
Or, we might find that money is increasingly not a requirement for commerce at all. We'd simply swipe our card, tap our iPhone, or wave our key-chain at the scanner and forget about making change at all.