Ever since its opening, the natural pitch has been criticised. Current model is very expensive to maintain and so a move towards fully synthetic field is considered, according to BBC.
At present the pitch at Millennium Stadium isn't actually at the stadium most of the time. It's grown in a different location and transported in small portions before every game, on special pallets. This is costly and still doesn't provide the optimum conditions to play in.
Problems with the field have been returning time and again ever since the opening in 1999. The stadium is simply too tall, shady and enclosed to secure sufficient sunlight and ventilation for natural grass.
The International Rugby Board has already approved the use of artificial pitches consisting of a stone base layer, on top of which is a thick black rubber shock pad and a covering of green yearn 5cm deep with an in-fill of black rubber crumbs. FIFA also allows artificial fields of proper quality and even though no football is played here for the time being, potential move for an artificial pitch wouldn't hurt Millennium Stadium's chances to host Wales again.