Why, WHY do they do this? Also, why is it walkers here and Lays everywhere else?

Opal Fruits - Starburst
Marathon - Snickers
Oil of Ulay - Oil of Olay - Olay
Jif - Cif (Although I think this one was to do with it not being pronounced correctly by people in some countries it was sold in or something)

I'm sure there's valid reasons for the changes, although I still don't understnad why opal fruits changed. I think the taste changed too.