If people use it, it is clearly providing a value to them. Why shouldn't the users try and sustain something providing value?

And even as a non-user, the more active developers and projects in this space the better - it's never good to put all your eggs in one basket. Will I personally donate? Probably not, but I see no benefit in trashing the idea of users donating.

I'm very suspicious of that number, I suspect that's the cost of a server and does not include any labor costs for server maintenance or dev salaries.

Volunteer run programs are nice but also dev time is money.