Writing in the Guardian, Hadfield, who is to finish handing over his Telegraph World Cup project today, said he was surprised by the fast online reaction to his comments.
"A few days earlier, I'd told my closest and most senior Telegraph colleagues about my decision - and the reasons behind it," he said today.
"Nothing I said during the debate would have come as a surprise, certainly not to the many senior Telegraph executives who are my contemporaries, alongside whom I have been privileged to work in print for up to 20 years."
Today, Hadfield outlined how print must change: "To survive, newspapers need to rethink radically not only their business models, but also how they manage their businesses; they need to overhaul outdated organisational structures; they need to consider how they relate to all their employees, to third-party providers of content and services, and to individuals with whom they may have no contractual arrangement whatsoever."
Newspapers need to rethink how they relate to their communities of users, "when they know next to nothing about members of their digital audience".
"No longer can newspapers survive by publishing at their readers, by talking down to them, by controlling what can and can't be written or said. In future, they will have to provide - and share, not 'own' - the online environment in which they can meet the needs of individual members of their community. They have to be part of social media, not monolithic media," he wrote.
Following Hadfield's appearance at news:rewired, a practical online journalism event that marked Journalism.co.uk's 10th anniversary, TMG issued a statement: "It was mutually agreed that [Hadfield's contract] would not be renewed. TMG is focusing its digital development on its Euston project and Hadfield had no involvement in this."
Hadfield was probably the first British journalist to leave national newspapers for the internet in 1996 when his son, then aged 12, had created Soccernet, the globally popular football website.
It was subsequently sold to ESPN/Disney for £25m and Hadfield sold his second venture, Schoolsnet, to Hotcourses, a company co-founded and owned by the shadow culture minister, Jeremy Hunt, in 2003.
Hadfield's long career in newspapers began in 1979 at the Wakefield Express. Later roles included assistant editor of The Sunday Times and senior journalist on the Daily Mail. He was chief reporter of The Express on Sunday and chief investigative reporter of The Express. Hadfield was twice commended as Reporter of the Year in the British Press Awards.