Harvey, eliminating the $1 bill would force the removal, reengineering, or replacement of many vending machines, and cause a hardship for many of their users. There are a handful of machines designed to accept dollar coins, and many, many, many designed to accept dollar bills. Yes, I think it would be fine to have coins instead of bills, but it would cause huge problems for a lot of people.
And, FYI, you can’t “enlarge” an engraved printing plate. They might be modeled on the same artwork, but the engraving is all new.