When an artist is commemorated on a coin, picking a famous and/or characteristic work of art is definitely a legitimate approach. In this case, well, Jan van Eyck did make several paintings that are probably self-portraits, such as the one on the €2 design. Two birds with one stone etc. ...
As for the €10 piece, van Eyck might be one of the persons in the mirror. He is not the groom though.

Christian