You must remember than the U.S. had not issued any commemorative coins prior to 1848. The true commemorative would not come along until 1892, which was the Columbian Half Dollar. I imagine that getting a commemorative coin bill through Congress would have been pretty tough in 1848. The way this coin was made, with a special counterstamp, could be done without Congressional approval. So far as I know, they were issued as normal coins, but they were probably given to those who had some "pull." Oddly enough, only about 200 out of the mintage of 1,389 exist today. Apparently, some of those who got them could not resist spending the $2.50, which was a decent amount of money at the time.
It would fit into my collection nicely. Maybe it will show up someday at a not too inflated price that I can afford.
The first (100) 1921 Denver Morgan Dollars were counter stamped/engraved by the mint to commemorate the only time Morgans were minted in Denver. If I remember the story correctly only about a dozen were actually stamped.