It was tried before back in about 1997 I think when the plate final was held at Wembley before the CC Final. Only did it once so guess it wasn't thought of as a success.
It was very much a success for both clubs. Raised a lot of publicly for the clubs playing at wembley. More than it would for at the shay. The semi finals were more intense, as the prise was to play at wembley. Thousands of fans from both clubs turned up to the final, by the second half came 50000 people were watching the match.
Not many semi pro players will have the chance to play in front of such crowds.
Plus wembley struggles to sell out, so it can only help boost the attendance