One big reason is money.
People have an idea in their head that putting on concerts is like writing a blank cheque but if you're renting out the stadium & facilities at a loss in the desperate hope you make it up in f&b sales or even worse paying a huge guarantee that basically requires you to sell out and have everyone drink 10 pints to make your money back, just because the promoter wants to fill in some midweek empty dates between the 'important' shows at the likes of Wembley and the Etihad then you at best make very little, at worst lose a lot.
There's a reason a lot of similar sized stadiums to ours are having a lot less shows in recent years, or shows that are cancelled late in the day because they're going to lose so much money.
Plus now the work at Villa Park has been completed it's a no brainer for a promoter to choose a venue in a city with a much larger population.
There's not really many Rammstein sized bands who want to play stadiums but won't risk the likes of Wembley.
The key to making the venue a viable business is the exhibition hall but you've got the NEC down the road which is some pretty tough competition.
