Two different mental situations:
1. Accumulating stable budget FOR RD&marketing from nobody (it doesn't harm anyone).
2. Unpredictably "diverting" funds FROM everybody.
Just imagine situation: MN ops decide to finance "Decentrilized exchange" (or even worse - something for MNs) - "diverted" funds FROM miner (also).
It'll be hell, miners: "They are robbing us! Why MY money is going to that f*cking exchange - I don't need it!" and so on.
What? Money is being diverted from miners either way, but one way means that it only gets diverted if a majority of voters wish it, the other way means it gets diverted anyway and nobody has a say in the matter.