The OO techniques do have their's place, but I would argue that that is not all about the flexibillity. It is for me in the lowest layer - source code, and is much more usable for the author of the code than for the 'general public', it's just too tightly coupled. Templating for webpages is a perfect example of a really powerfull technique well separated from the source code.
I agree that OO is not only about flexibility. The main point for me is that the OO approach can match the "problem space/world" very closely. So it's mostly about modelling, the flexibility can come for free if the former was done "right" (for your favorite definition of right, i.e. there more than one way to do it ;-)