It is a very known fact that a normal human brain works on a power of 15 watts. Hence, it is biologically not capable to notice those changes which are made in a flash of a time or just made on an unimportant base. In psychological terms we call it "Change Blindness", and here is where, the Brand Makers play their game.
Yes it might seems to you that your favorite brand/product is same and unaltered for last so many years, but you will be surprised to know that lot many things into it have been removed/added and altered.
But the brand will play with your "so called 15 watts powered brain" and will project the product packaging in such a manner that your brain will not be able to notice those changes.