Cary,
No explanations are necessary. If people do not contribute that is there business. If the site is in financial difficulty, there are enough contributors to see that it is kept solvent. Maybe participants from other nations do not contribute because of the currency constraints. Whatever the reasons, it is a free forum that depends on voluntary donations. I don't want to speak for Ran, but it changes the ethos if there are forced contributions. Then there is a sense of entitlement which some seem to act upon in any case. But voluntary contributions and Ran's support are what makes this an open forum. Let's keep it that way and depend on the positive side of human nature. I'd rather it stand or fall on that as opposed to another structure.
Even these reminders, we usually see them this time of year, are a bit invasive for the spirit of the site. At least that's how I see it.