[Stooky Bill]

 just as Central doesn't really scream 'Midlands' to anyone.

It describes the part of the country it covers - the centre of England. 

Thing is that between the two broadcasters all the geographic terms for many parts of the country have been taken. So the ITV news in the South had never had the word South in the title as there's always been South Today. 'Anglia' has always been an ITV word and 'East' a BBC one. 

'Midlands' has always been what the BBC regional news was called, so the ITV company took another geographic term.

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Why have Meridian and Granada's names survived in the names of their local news programmes? Neither name describes the region.

Meridian kinda does. The explanation behind the name was because the Greenwich Meridian went through the region. Of course it goes through a couple of others too, but I suppose in their case it's roughly the boundary between the South and South East part of the region. 

But what else to call it? 'South' clashes with the BBC's programme and anything 'coast' is a bit odd in Oxfordshire. TVS's Coast to Coast programme name made little sense in places like Reading back in the day