The one that annoys me the post is when we hear "isn't it wonderful, I can go to XX Airport or YY shopping centre without having to change".
This has come up a few times in this thread so I'd like to attempt, if I may, to put the matter to bed.
It is not
necessarily about giving those direct 'journey opportunities' through the core to places the other side of London.
London termini are filling up, and London cannot cope with their expansion as demand increases - although it's in a lull at the moment, it's likely it will continue to increase. There is simply
not the capacity to continue ramping up services to them. See: how TL/GN cannot plan to use King's Cross for trains diverted from the core.
Increasing the size of London termini is
not a futureproof solution. The problem will only inevitably roll around again - and it will - and by that time, it will be
even more difficult to add terminating capacity in the city centre.
Where there
is space, however, is at the ends of the route. So by terminating trains there, and not in central London (and perhaps some time in the future expanding those termini?) we've reached a
futureproof solution to these capacity issues.
It's a much more efficient use of space to run trains through London than to terminate them there.
Yes, the core has its reliability issues. Yes, maybe it shouldn't be two-track throughout.
But, existing London termini are not without these issues.
Just imagine it doesn't say 'Luton' on the front, and says 'London Blackfriars' instead. That's for people travelling from London northwards to worry about, and a few select people making the thorugh journey on the train.