It is quite common to take a performance and set it in a time and location other than that for which it was originally written. This is almost the default approach Shakespeare and many operas. Nevertheless, it is worth asking what is gained and also what is lost when anachronism becomes a default mode.
In the case of Medea, we have Euripides play set in a Corinth that isn't recognizable as such. Instead it is set in a kind of nowhere at an indeterminate although reasonably contemporary time (a camera phone makes an appearance and so on). This shift jars too much with the context of the play, because in an attempt to make Medea somehow relateable, we loose the sense of just how different her world is from our own.
For Medea, gods and oracles were very real things. When she claims to have seen her ancestors, she actually saw her ancestors. When she prays to Hecate, we need to understand Hecate has a real presence and ontological status greater than that of a belief. Similarly Jason is not merely an middle aged man, but an epic hero. These characters need to be lifted up and made larger than life, not humanised. Consider: can we, in a contemporary, reasonably believe that a chorus of women would not rush to child services upon hearing Medea's plans?
The result is unfortunately that rather than Medea's story becoming a timeless one, the contemporary setting reduces its impact and emotional weight. It becomes a story from a tabloid. It would be much better to set Medea in outer space, or a similarly fantastic context rather than this.
Medea is at the National Theatre until September 4th, 2014.