I used to work at a very large and entrenched publishing-cum-tech company, too. Sounds like they were different companies, but very much the same rationale for migrating to a well-known cloud service provider. The ossified and entrenched IT department was becoming one of the biggest challenges to quickly reacting to market challenges and opportunities, and was long overdue for a few boots planted firmly to the rear end.
The cloud was probably always more expensive if you only considered the cost of computers. But it was about so much more than that. Mostly, it was about creating a hostile environment for the BOFHs who were creating a hostile environment for everyone else.
Another way of framing that: BOFHs went from being necessary to the business to preventing the business from acheiving its goals, and got replaced by competition that was more amenable at a higher price.
They weren't seen as so unprofitable they had to be eliminated, but unprofitable enough that competition could triangulate their price vs pain.
The cloud was probably always more expensive if you only considered the cost of computers. But it was about so much more than that. Mostly, it was about creating a hostile environment for the BOFHs who were creating a hostile environment for everyone else.