I thought the idea of SSN commissions were to cover the cost of providing the staking infrastructure and reward those SSN providers who contribute to the ecosystem (through delegation) but I don’t think any SSN provider should be entirely funding their projects in this way - setting a 4% base rate reduces competitiveness for stakers in order to maintain unsustainable business models.
I would actually argue that both staking rewards and SSN commissions should be reduced!
As per the whitepaper, Zilliqa was supposed to have transitioned towards reducing block rewards by now (which there is a strong argument for - see this post: Zilliqa Incentive Layer ), which would also reduce the staking rewards and therefore SSN commissions.
So I think projects should be focussing on more sustainable means to bootstrap their development rather than SSN revenues.
I would also suggest that out of miners, SSN providers and stakers, stakers are the least likely of the 3 to sell their portion of the block reward…