Well, there is actually a large body of research on that. In a nutshell, rationality and emotion do not run counter each other but rather feed one another. People develop strong senses of emotional attachment to companies particularly if they become loyal to them, be they an airline, a car manufacturer, a restaurant or a newspaper. It comes with a mixture of cognitive and emotional causes, from dear memories that you may associate with the company (think of all the people here who flew BA as little kids for instance) to gratitude when the loyalty has been reciprocated (that time BA waived the rules for you and rerouted you for free even though it was your fault that you missed the plane, or that lovely upgrade etc), and how your own behaviour, including consumer behaviour becomes part of your self-perceived identity even when you don't realise it (I tend to wear x, I love to eat y, etc).

As I said, it would not be practical to summarise it here, but that has been studied abundantly (and at times interestingly!)