Because you don't have to pay and most people don't, + the reasons from my previous comment.
On the other point: Discussions are at the core the movement, and how to do fundraising "right" and how to use funds is worth discussing and gets discussed. But that it is needed in general is obvious I think. What else should be done? Let all the projects run out of funds and call it a day? That would mean the end - and today Wikipedia is more needed than ever.
As a liberal I've always had to fight the tendency we have to not see legitimacy sinks in the name of politeness. Lately I think people are willing to listen and I'm working on ways to explain this to people who don't bellyfeel them already.
Since I was a kid I thought that the endless fundraising drives destroy the legitimacy of public television. At the bellyfeel level it is visible moneygrubbing, but at a political science level these run side by side with ads promoting the sponsorship of the Archer Daniel Midlands corporation. ADM is notably the prime beneficiary of ethanol subsidies in the U.S. that wreck the environment and make farmers go broke spending money on nitrogen fertilizers that kill off life in the ocean off the mouth of the Mississippi River.
The trouble is that small donations don't give voice, but large donations do.
I can logically justify how I feel about fundraising drives on PBS, but I feel a resonance that causes me to feel the same way for Wikipedia -- I don't know what the Archer Daniel Midlands corporation of Wikipedia is, but it probably exists. Finding out that they don't really the money confirms this feeling.
On the other point: Discussions are at the core the movement, and how to do fundraising "right" and how to use funds is worth discussing and gets discussed. But that it is needed in general is obvious I think. What else should be done? Let all the projects run out of funds and call it a day? That would mean the end - and today Wikipedia is more needed than ever.