Many coin collectors appreciate the history associated with an old coin. So, appreciating ancient coins, artifacts from antiquity, is easily understood. Yet many coin collectors will not have a single ancient coin is a typical collection.
One reason people do not include ancient coins is that there is a misconception that all ancient coins are expensive. True, many ancient coins are expensive, but lower grade coins often are not.
Of course, higher grade coins are more desirable. Many well worn coins look like disks with little detail. This is because no one has a can of pristine ancient coins hidden in an attic from the year in which they were minted. Ancient coins are usually dug up after years of having been buried. This is not conducive to having great specimens. Also, ancient coins were minted before mints had machinery to put pressure on planchets with well engraved dies. Some ancient coins, those minted for military payment, were often minted by portable mints that went with the soldiers by a person who applied pressure with a hammer. Yet despite this, great specimens do occasionally come available.