If we remove the author rewards from the equation then "investors" will follow the path of least resistance and simply turn into passive users an content producers will just leave. This will hurt the distribution of stake.
Although not perfect "POB" is a good enough mechanism for coin distribution. We can argue about the percentage of the inflation that goes into the reward pool but I think that abandoning it would be a mistake. A side effect of having a reward pool with POB is that it creates an army of free advertisers and advocates for the blockchain.
As an investor I do not mind directing a good portion of the inflation for content production. In time a percentage of those content producers turn into stakeholders and it's essential for a DPOS system to have a wider distribution of stake.