There are at least two very valid reasons why diverting a portion of the block rewards to development or some other project such as marketing is not a good idea at all.
1) Regulatory compliance.
In summary one needs to keep one's hands out of the till, block rewards, in order to keep the regulator away.
If this is true, then ZCash is going to face real problems as an US-company, or better said their miners.
It is not just Z.Cash. There are many crypto - currencies that have this serious regulatory risk. Please read the guidance carefully rather than simply take my word for it. The question to ask when reading the guidance is: Does a particular crypto currency qualify as a "De Centralized Virtual Currency" under the guidance?
I wouldn't care too much about getting deep into these law discussions. If regulators (aka the lobby) really want to bring down/illegalize a crypto currency for whatever reason, they will do it regardless of anything. At least that's the way how Europe works, where established law is getting pooped on by governments all the time.
This overall is an argument for currencies that work without a company behind it. Developers should also rather not be US citizen.