I am sure Grandma would have preferred to deal with sore crackberry thumbs instead of worrying about tuberculosis, polio, scarlet fever, diptheria, smallpox...
I'm a Blackberry user and my thumbs are in great shape. Breaking the chain of the coporate office is worth to me a sore thumb or more.
Also, I don't look at it like an 'addiction', but rather a means to be much more responsive to my customers. Blackberry has changed my work routine for the better more than anything since the personal computer. Not sitting in rush hour traffic alone is worth more to me than any 'expansion' of my work day.