Why would a large corporation switch from Microsoft Office to a generic version (OpenOffice)?

Answer 1

It's all about the money.
Programs like MS Office require a certain amount paid for licensing for each computer the software is used on. In a large corporation, that can run into the tens of thousands of dollars, so it isn't just a matter of one $700 program vs. free .... It's a way of saving a LOT of money.
Also, since open office if open source, their IT people can tweak the program to the individual needs of the corporation.
Makes super sense to me!

Answer 2

MS Office requires licence for each computer. It's expensive.
OpenOffice is free.

Answer 3

MONEY!