I'm saying from now and going forward, imposing a "mandatory tax" or "mandatory donation" is going to get more flak than any benefits. Optional donations, fine, but nothing more.Every minable coin has an inflation = tax for current holders.
With Bitcoin it is a kind of dullness = all these "taxes" are sending to miners (so they don't support innovations).
With DASH it is much more effective now - because MasterNode Operators are interested in innovations so SOME of them will donate voluntary.
But it is still not the most effective system IMHO.
And I hope if more effective system exist - DASH will be the first player who discover and apply it.
And if there is no more effective system then now, it's also OK - so no one can compete with DASH.