Often, words shift in meaning towards more general senses, often as a result of their use in metaphor, and sometimes just because of a preponderance of people using them without understanding their "proper" meaning. Shifting of meanings of words is a natural part of the evolution of language, and change can be good. There's no point in getting upset about words shifting around. Most of the words you use now used to have a different "proper" meaning, in some cases even the opposite of its old meaning (consider "nice").
But sometimes when we lose the meaning of a word to drift, the language loses expressive power. Suppose a word has a precise definition, and no other word has that same meaning. Now the word drifts to a more general meaning, largely because of misuse by people who don't really understand the original meaning of the word. If you, perchance, need to express whatever the word originally meant, you're stuck with the extremely clumsy option of saying, "so-and-so, only by the older definition", or of using a phrase to explain it, both of which make the whole sentence they're in become awkward and threaten to overwhelm whatever point you're making.
I mourn, amongst many others, the words epicenter, haiku, and fantastic, as well as the phrase quantum leap, a champion of lost words in that it means the opposite in lay use as in its original scientific use (and Merriam-Webster only records the former). Post your own contributions to the semantic graveyard.
On the mirror image of the same topic, sometimes a word or phrase, having been broadened, becomes a point of contention for outliving its original metaphor. These fossil phrases sometimes are just a metaphor that's lost its original analogy: "lock, stock, and barrel", "blowing off steam", "hoist by his own petard", "three sheets to the wind", and more.
But consider how the TiVoCommunity forums kneejerk a reaction to the word "tape" -- there's no tape in my TiVo! Well, there's no dial on their phones, either, and I expect most of them have been using word processors instead of writing for a long time. Should we be recording, "ringing up", and composing instead? Does it really matter? In a way, this is the same situation: there's no longer a word that uniquely means "to record onto tape", since "tape" now just means "to record" -- and I suppose someone, somewhere, needs to make that distinction. I just have a hard time imagining who and why. Am I being hypocritical to object to the loss of the original "epicenter" but not the original "tape"?