The magazines and books always seemed quite inexpensive, so I never dreamed that money was the main reason they emphasized the preaching work so much, but of course I was wrong. When you make things with all volunteer labor, then have free labor to distribute them, there really was very little overhead, and even those small amounts added up. But it was a business model that was doomed to failure.
They tried to make up for the donation arrangement by trying to make people pay just as much as they used to, then turn in any donations raised, but that was never going to work. There was always going to be those who just didn't bother to pay or were broke, it's impossible to enforce. And how do you tell them to pay more when the costs rise? You couldn't. And requesting donations at the door was a bad idea also. It probably sounded good on paper but didn't take into account basic human nature. Most magazines end up not getting placed anyway and I don't know about others, but I just was not going to ask for donations, it just felt wrong, like I was begging, so awkward.
But I think they would have been in trouble financially even if they weren't forced to stop charging for the literature. Due to changes in society, more women started working outside the home, so they were not home during the week and then too busy on the weekend to talk. People became more suspicious of strangers knocking at their door, less likely to listen. In many areas territories got overworked, people were sick of being bothered and those that did take the literature figured out it just meant they would come back sooner. I also think most JWs just don't like field service for the most part, so they weren't motivated to do a good job, and soliciting donations door to door is hard, very few are good at it. Most JWs just want to "get their hours" and go home, they didn't really care if anyone listened or not, there really is no urgency to the preaching work anymore, not like back in the sixties and seventies.