My definition would be:-
1)....More cost effective than being in London, as Milton Keynes is one of the "New Towns".
2)...National Rail see this move as still being on a main national rail link with good modern station facilities. If a national rail oriented company did not see Milton Keynes Central as such a station, with suitable rail facilities, why would the consultants working with them have come to this decision?
3)... HS2 is just another part of a European rail initiative to link major parts of the economy of the European Union. Britain has lagged after France shamefully so to most thinking forums on transport. But it must not be viewed as something akin to THE HOLY GRAIL of railway planning. It just seems to be so, because Britain is 30-50 years behind the forward railway thinking in other parts of Europe. It would be laughable...were it not such a condemnation of British railway thinking.