NPC's that block or distract the party from achieving their goals simply because they are too self absorbed, or are greedy, or are following there own agenda can be great fun. They help bring the world to life showing that the PC way is not the only way.

(My little old lady who was just trying to walk to the next town to visit her sister generated 2 hours of roleplay as the party felt obliged help her).
But I suddenly thought, what if the BBEG isn't bad or evil. What if he/she/it is simply trying achieve certain goals (see the thread linked above) that come across as evil. Not an original thought by any means but it got me wondering if other DM's have used a BNG (big neutral guy) or a BGG (big good guy) in their campaign as
the opposition for the PC's.