For me the level of service is what drives me towards a FFP. I do not use an airline because of Elite status, but if I have Elite status it is normally because I am happy with the airline (comps excluded).
This applies to Business Travel, where Elite status makes little difference to service received. For leisure, I try to use carriers I am Elite with in order that I get some benefits.
As for the number of programs I am enrolled in (or rather actively use) - this is reducing every year as a result of alliances.
Nick