The problem with your argument, Hippenine, is that it would not and does not interest headline chasing politicians.
Tinkering with the trainset to make it more reliable, provide more and better connections and increase the size of trains does not make big headlines that tick all the necessary political boxes, ie:
a) visionary (claimed)
b) bold (supposedly)
c) advanced technology (for UK anyway)
d) envirnonmentally beneficial (debatable)
e) anti-aviation (naturally)
f) Easy for the Sun reader to understand (patronisingly)
Moreover, building one high speed rail link is easy for the bears of very little brain that make up the current blighted crop of politicians to understand!
One of the key problems of building a line like HS2 is that who knows what demand for transport links will be required in 20 years hence. Ripping up areas of outstanding natural beauty for an unknown quantity should be very hard to justify.
The beauty of air travel is that route networks can change on a daily basis and don't require £20 billion of infrastructure every time you want to fly to a new city. The airports are there already, the planes are there, and, for sure, the pilots are queuing up to be there.
As to the argument that it will relieve capacity on other lines, ask the people of Kent what has happened since HS1.....