Every advanced society faces an aging population. This population will put massive strains on healthcare expenses. It could also strain the economy as the elder population collects public sector pensions and slowly depletes its savings (i.e. retirement funds). The latter effect could be mitigated by automation.
Paradoxically our success in treating diseases that kill us now will merely make us victims of potentially more terrible diseases in the future. Look at the experiences of centenarians in the last decade:
http://www.cdc.gov/nchs/data/databriefs/db233.htm
Alzheimer's will become increasingly common as will cognitive decline in general. What happens to all those people who don't die of cancer or heart disease? They will often succumb to slower acting chronic diseases involving long-term states of suffering and mental anguish.
The way out of this mess is to treat aging itself, not just the diseases that currently kill us. SENS targets the underlying mechanisms of aging.
Research into negligible senescence can also lay the foundation for potentially profitable therapeutics. Unlike the disease-centric model the total addressable market is nearly everyone.