Redesigning a heritage brand is always a delicate operation because the creative needs to evolve subtly so that new consumers are attracted to the brand but existing consumers are not alienated by the changes. With a brand such as Mr Brains, consumers have been generally been brought up with it, there is an attachment to the brand and taking the design too far can have a detrimental effect. An understanding of the core consumer and their association with the brand is key to retain their loyalty.
Sometimes, with heritage brands like this, there needs to be a staged approach where the brand/packaging is evolved in smaller increments, which will lessen the impact for the existing consumer.