I think it would be easier to go from PDO/MySQLi to MySQL, and learning MySQL leads to bad habits (hence the need for prepared statements) so I'd say learn PDO/MySQLi first, and then deal with MySQL if you need to.
I don't necessarily disagree with you about that. My point was just that discouraging learning the MySQL API altogether is not a good thing.
True, but for many beginners the perceived extra work seems to make it a "one or the other" proposition. My feeling is that in that case, make it PDO or MySQLi because they're more secure and if you learn them and need to use/maintain MySQL you can easily learn it or better yet, upgrade it top prepared statements.