Hi Nigel: No doubt there are many reasons but one of the simplest reasons...
A secular humanist that is 'missing something' can easily add on Buddhism. Since Buddhism has no God, just self and it's own awareness the easy route to quasi-spiritual feeling and peace is adopting a religion that will not interfere with the core beliefs of the secularist.
The very pliable Buddhism can morph to whatever moral constructs a society has, there is no repentence, no God or conviction, no authoritative law or commands, there is no promise of hell or heaven just a mantra..."peace with one another" as John Lennon sang in his hallelujah..shift to Hari Krishna song.
Buddhism is just another of the names the 'broad path that leads to destruction' is called. They are already hell-bound via secularism, but renaming it Buddhism and modifying a few behaviors will distract them for a while.
This is one of the very interesting things I've found in researching atheism/secularism it always seeks to fill the void that 'no God' creates, and surprisingly the atheist secularist has little qualms about adding eastern religions or new-age spirituality.
Contradictory? Yes, Strange? Yes, but entirely normative when you look at atheist/secular societies over the last 300 years.
A true move of God in the Church and the society is the only answer and I believe praying for it is the right response.
