Unfortunately, as interesting as a mental exercise as "Languages are Alive" is for mental gymnastics, it has some serious flaws and negative implications. None of these are as problematic as the lack of predictive power and the lack of testability.
The first is caused by the current inscrutability of languages. A good foundational theory for language requires making predictions about what structures languages can, and cannot have. Unfortunately, the number of known 'language universals' seems only to shrink, not grow, as exceptions are found. As perusing the universals archive will show you, most previously 'absolute' universals are now merely statistical as a counterexample is discovered. We know so little about so many languages that we are sadly uninformed in many ways about what it really is.
Our second problem, that of testability, comes from some weaselling in the general hypothesis of "Languages are Alive", it's a bad hypothesis because any test that could confirm it could be hand-waived away as "Languages are not that kind of alive!" Our definition of life from the get-go was overly broad, as you may have noticed from how much was being sucked in as being 'alive'.
However, the idea that languages are like living things is not new, phylogenetic trees have been constructed, especially for Indo-European, that show languages related like families and species. If it were not the tail wagging the dog to use this as evidence of languages evolving like biological species (the trees were created under the assumption that languages evolve that way, see 'wave' models for an alternative that does not use that assumption but still classifies languages well) it would certainly seem that language is alive.
It is, in that sense, a useful analogy. One can say, for example, that English 'evolved' it's vowel system from the 'original' old-English [a], [æ], [ɛ],
[i], [ɔ], [u], [ə] and [y] to modern English's [i], [ɪ], [u], [ʊ], [ɛ], [ə], [ɔ], [æ], [ɑ]. This is not 'wrong', but it is an analogy, a metaphor, not an actual hypothesis for what is happening.
So, I hope you had a great Christmas, great new-year, and have a wonderful 2013!