I don’t know the reason for the Taco Bell change, but I do agree the brand refresh was appropriate. In my mind, they made some good decisions and some not so good decisions.
How do you know when it’s time to refresh your company’s brand? A “brand refresh” is simply keeping the good elements of your brand while improving the not-so-good. Most established companies have equity built up and can be recognized by certain elements of their brand. Those are the parts to keep.