What's of actual importance to investors is the closed-loop economy, in other words the viability of the system to generate revenue instead of being a perpetual drain in their pocket.
The 10% system that you propose is good, not in actual terms, but in things affecting people perception. But then there's the lack of incentive to hold SP. The system may need a redesign in that aspect.
The concept of perpetually paying rewards is entirely flawed.
(Steem is fundamentally flawed in so many facets, and that is why I place 100-to-1 odds on its price ever rising again.)
The only point was onboarding and building a commerce driven ecosystem. The rewards are not needed after that, because a vibrant, profitable, decentralized commerce-driven ecosystem will trounce Facebook and everything else.