care of the elderly in Spain - a reason behind the new residency requirements?
Another reason may be that Spain fears the consequences of having a huge elderly expatriate population on its hands. While some might feel that this is a 'down the road' problem - expat charities such as Age Care Association etc are dealing with huge numbers of non-Spanish citizens (who immigrated to Spain in previous decades) and many of whom are now in poor health and without the financial/medical/social supports to provide care and comfort.
Quite often these unfortunates have never signed on the Padron or have never applied for Residencia and as a consequence they find themselves in a medical/legal limbo. Indeed even those in relatively good health might suffer from loneliness and isolation due to a partners death/divorce etc. It is a major problem that partly informs Spanish immigration policy.