I realise you are a WUM but let me explain a few facts.
1. The semi finals may have been at Wembley for a number of years but nobody ever knows what time they kick off and on most occasions which day
2. We were told many years ago that semi finals would be played at Wembley to recoup the money spent on the rebuild, which incidentally should never have been in London but that's a different argument. However the assumption was that these games would revert to a neutral stadium nearer where both clubs are based.
3. Many people have young children who they would like to take to a game, hard to plan if this is feasible if they can't book cheap travel, hotels etc
4. The last train back to Manchester is 21.01. The later the kick off the less chance of being able to travel that way for the many people who prefer that mode of transport
5. To announce the kick off times for two games shouldn't take eight days and it's taking the piss
6. There is nothing special about Wembley for most people
7. Whether we like the place or not this game should be held at the swamp and if the FA remove all their hangers on then most, if not all of the real fans,who want a ticket will get one