Is doing a PhD just for the university requirement is a good idea?
In my university back in Mexico, they had something similar, if professors want to get ahead (income, professional, etc) they had to an additional degree (Masters, PhD)

I think that if you do not have the motivation, you'll have a lot of problems, doing a PhD is already a taxing endeavor, in the sense that many times you'll start wondering wether this was a good idea or not. 

As in many things in life, if you do this because you are made to (like students that go to college because their parents want to) you'll have lots of resentment.

However, not all is lost, you can try looking for something you are really passionate about, and then try to do a PhD on that.