From my perspective the balance of evidence suggests that the progressive shortening of average telomere length with advancing age is a marker of damage and dysfunction, not a primary form of damage in and of itself. That telomerase gene therapy has lengthened life span in mice means that reseachers should focus on how this might be happening rather than assuming it is because of telomere lengthening: for one thing telomerase has many functions, not all of which are at all well understood, and for another mouse telomere dynamics are quite different from those of humans.
Nonetheless, there are plenty of folk who think that we should focus on telomere lengthening, such as this advocate who holds to the programmed view of aging:
You would think that the 2009 Nobel Prize might have done more to raise the profile of research in telomere biology, but the field remains a specialized backwater of medical research, and few biologists (fewer doctors) take it seriously as a panacea for the diseases of old age. If the National Institutes of Health have money to put into heart disease and cancer and Alzheimer's and Parkinson's diseases, there is no better place to invest than in telomere biology. Research on these diseases commands multi-billion dollar budgets, because they are considered "medicine", funded by NIH, while telomere biology is considered "science" and is funded by NSF. The total NSF budget for all cell biology is only $123 million, and the portion devoted to telomere biology is a few million. The private sector is doing a little better - there are several companies selling herbs that stimulate our own bodies to liberate telomerase. But this is short-sighted venture capital, and what we need is focused research with a ten-year vision.
There is good reason to think that telomere length is a primary aging clock in the human body. The body knows perfectly well how to lengthen telomeres, but chooses not to. All we have to do is to signal the body to activate the telomerase genes that are already present in every cell. Of course, there is no guarantee that this will work, but compared to the sluggish rate of progress on individual diseases, it's a pretty good bet, and the target is rather simple. IMHO, it's worth a crash research effort.