Alison Wolf has a piece in The Observer where she details the decline in charitable giving and involvement in the UK. One of her points is best viewed as being an advance, despite the effects upon such endeavours: the freedom of women to enter the paid workforce in a manner that just over a generation ago would have been unthinkable. A second is most certainly not an advance :
One thing that has certainly changed is the arrival of modern regulation. Here's a simple thought. Imagine there are no Scouts or Guides and a latterday Baden-Powell appears. Could he move from a small camp for 20 boys to a rally of 10,000 Boy Scouts two years later and a tripling of membership in the following two, all based on local volunteers? It's a stupid question. Today, you need Criminal Record Bureau clearance and specialist training to do pretty much anything with under-16s.
And here we need the ritual invocation of M. Bastiat. Assume, just for the sake of argument (not an assumption I would be happy to have to support, I regard these regulations as having done almost nothing to curb the evils they are aimed at) that such checks and clearances have prevented some crimes. We might even be able to see such in declining rates of such events. But what we can't see, but which has cost us dearly, is all the things that have not happened because of the deadweight costs of those very rules and regulations.
There's one more point:
It is hardly that the need has vanished. The welfare state is hitting its limits.
I agree that the welfare state has both expanded mightily and also does not cure every ill, that there is still a necessary role for private charity. I also accept her outline of the decline in people making those charitable efforts. But just to be contrary, might it be the very expansion of that welfare state that leads to such hesitancy? This graph  of private overseas aid by country is instructive. While there are problems with it (it's not per capita nor weighted by GDP) a quick eyeballing does seem to indicate that the larger the domestic welfare state (and quite possibly the higher the percentage of GDP spent in official aid) the lower the private charity. Domestically this could be explained by there (ha ha ha!) no longer being a need for it as every want is catered to, but this clearly doesn't hold overseas.
Could it be that, as with such things as investment or borrowing, so with charity? That as government demands that we do things centrally and via the State, that private activities get crowded out?
I admit, that does lead to a very odd idea. That it isn't so much that if the State retreats then private charity will take its place, but that we should pull back the State in order that individuals might exercise their moral senses by helping directly their fellows? There's more than one best selling book been written on the way that that last activity makes us better people.