Bristol is a far better airport geographically makes perfect sense .
I'm sure if we tried to develop Cardiff Airport the environmental outpouring will be deafening as it was for the M4 relief 
https://www.bbc.co.uk/news/uk-wales-48512697
"" The Welsh Government will not build the Ł1.6bn M4 relief road, First Minister Mark Drakeford has decided.
He axed the scheme because of its 
COST and impact on the environment.   ""