Why do you feel compelled to draw attention to the loss of your grandmother?
Um, because the person loved her, that's why. Why do you feel compelled to take issue with it?
The point of a dedication is to hallmark an intense work of labor or of love with an emblem of personal significance, and to seal that work, in a sense to elevate it, with the idea that all of the work we do is in some sense personal -- to ourselves, and, to the degree that we are influenced or driven by those important to us, to those others as well with whom we share our lives. If one can dedicate, of all things, a plaque on a park bench, then why not dedicate our work -- which is our time and therefore a fundamental material of our lives -- to someone we love? Why on Earth would "professional" mean "devoid of personal investment?" That's ridiculous and, in fact, flies in the face of the working wisdom of many successful firms who have become well known in recent years by finding ways to make work more personal, by allowing workers to bring their dogs to work, or by providing childcare or concierge services.
There's no harm in this at all and there's much to be gained if the coder, by virtue of his or her dedication, begins to take a personal investment in the maintenance of the code that's been signed in this way. Yes, I'm sure that we could think of ways that this could get out of hand or become problematic. But killjoy hand-wringing and fussy sniffing aside, I believe that coders should absolutely make a personal investment in the work that they do.