I think it is sad that so many good ministries in the States ask for donation as their main funding source.
They do not hold rally, preaching to crowd of people in spite of the abundant resources available directly to them. And they compensate this lack of income to "duty" of christians "supporting" their ministries.
I'm not saying that this sort of funding is at all negative. But I bet if I ask those like MacArthur, Sproul, etc. what's their main source of funding to their global ministries? "Donations from listeners" is their response. There is no distinction of offering, no distinction of Christians in the "supporters". With this kind of superficial comfort, there is no need of Gospel battle in a more personal way, the same personal level between God and man they have been preaching on radio. The kind of preaching that's less confrontational, less personal.
Knowing their conviction, I wonder how they teach others not to just stay at home listening to the radio for spiritual nourishment. If they have gained such fame, are they satisfied with just having people in their own churches in their own towns? This is the reason I will have more respect on Tim Keller, despite the problem myself and the others have commented on the issue of The Manhattan Declaration (Affirmation of Marriage as only between one husband and one wife). Which of these have brought their ministries to New York City? Sad indeed.