Why not just come out and call them HS2 DENIERS?
There are to say the the least huge questions over this project -
the sheer grandiosity of the new city centre developments seem to have more to do with enriching developers rather than economically providing extra capacity is one of them.
That sounds like a valid complaint to make - I can see your argument - I'd rather argue about such things than the fact that the timetable at Oxenholme isn't yet set in stone for the 2030s (despite timetables at many stations not yet being set in stone for a couple of months time!).
I suppose part of the idea is that they can't easily accommodate four hundred metre trains within existing stations (even if the platforms could take such lengths, there's going to be reliability problems trying to path eighteen high speed services per hour on the Euston corridor when they are at the mercy of congestion within the current lines at New Street/ Piccadilly/ Leeds etc - having segregated/separate stations makes some sense.
I'd like everything to be all in one place but realistically most big stations are already pretty busy so it'd be hard to find platform space for the HS2 services at them, without taking future growth in the 2020s/2030s into account. Eurostar wouldn't be as reliable if it was reliant on "metro" services clearing junctions around London Bridge etc.
Plus, if you build the HS2 platforms within the existing stations (or directly underneath, as I've seen suggested) you could face long disruption to existing passengers - we'd have people complaining along the lines of "why should my regular commute from Longbridge into New Street be disrupted for months at a time so they can build these HS2 sections, for the sake of rich businessmen etc etc").
And also the "sorry, but there's no space to increase services from Longbridge because all the spare capacity at New Street was taken up by the 400m platform for HS2 services, so any improvement to local services is hamstrung by the decision to try to accommodate HS2 services within the existing station". Maybe, if we were building HS2 in the 1970s/1980s and had plenty of space and spare capacity at New Street/ Piccadilly/ Leeds etc then we'd have found room for the High Speed services within the existing station footprint but things are busier now - it's enough of a struggle to cope with current service levels - e.g. look at the money they are spending at Leeds to remove a car park to put one extra platform on the "Harrogate" side of the station.
So, if you are going to have HS2 platforms separate to the existing platforms then why not spend a few quid more on creating "destinations", some civic pride in a new hub for the city that could attract new development - some businesses etc will want to have their premises near an HS2 station who might not feel much prestige being located next to a station occupied by Sprinters chugging away.
Brunel and the likes didn't build austere stations with a couple of bus shelters and little else - they built grand stations - cathedrals - Victorian stations were over-engineered partly because they were landmarks, they were sources of civic pride. Do we have to restrict station design to something as dull and functional as the British Rail WCML of the 1960s? The vast majority of the money will be spent on the hundreds of miles of track, signals, trains, bridges, tunnels etc - spending twice as much on a "nice" station rather than a "Tesco Value" station isn't a huge amount more - we always complain on here about how basic a lot of modern stations are, how they don't capture the imagination like a Paddington or a York does... I'm comfortable with spending a few quid more on having "flagship" stations.
Or, to look at things from the other perspective, look at the problems we are going to have at Sheffield Midland in accommodating HS2 services within the existing station - there are no spare platforms as it is before we give up the longest one to dedicate to HS2 - we are going to have potential for HS2 services being delayed and missing their slot further down the line because they clashed with a 150 on the Hope Valley stopper (or whatever replaces 150s in another decade or so) - Sheffield is going to struggle to cope with HS2 because we are trying to keep everything within the current station - in comparison, places like New Street/ Piccadilly/ Leeds will have some local capacity on current lines freed up by removing some (not all, but some) of the fastest services from the equation - e.g. the scope for more "local" stops to be accommodated on the Coventry corridor.
It seems that Coventry will get a poorer service after HS2. There's talk of adding more local services that stop at halts like Marston Green and Lea Hall with less expresses
You can call Marston Green a "halt" if you want, but that's a work I'd associate with quaint backwater stations on a GWR branch line (the kind that feature in thousands of model railways).
To me it looks like a suburban station with roughly 800,000 passengers per annum that cannot currently have more services stopping there because of the number of non-stop services zooming through - once some of those non-stop services are replaced (by services on HS2) then there's room for more services to stop at places like Marston Green - a station which would probably have many more services stopping there if it weren't on a two track line with 390s passing at high speed.
Same goes for Lea Hall, albeit with around 600,000 passengers per annum - not tiny numbers - but hamstrung by being on a line where there's no capacity for more local trains (because anything stopping there would soon have a 390 breathing down its neck.
These are stations that should benefit from HS2 though.
