They did it to Central before, which since the ATV days was jockeying for second place with Granada behind the London franchises in terms of producing the most ITV network programming before being closed, they produced a lot of the quality ITV's sorely missing, Central made the likes of Auf Wiederzehn Pet and Spitting Image, and ATV did The Prisoner, the Muppet Show, Thunderbirds etc. And the likes of Anglia and the various South of England franchises used to produce their fair share of national programmes.
ITV's strength was always in the regions, they're not going to gain any viewers peddling Londoncentric shite.
It all started to go wrong when Thatcher got rid of Thames in favour of Crapton