Yes rewards can attract users but beyond a certain point it is unclear that the effect is further increased. If we give away $100K/day we attract users. If we give away $1M/day do we attract 10x as many users? That is far from clear.
As far as increasing the value of the reward pool, that is true to an extent, but if so it would only be by the mechanism of increasing the value of STEEM, which to me can't be viewed as a bad thing.
I have pointed this out many times, but I just find it amusing that people pretty much admit that Steemit sucks as a site so damn bad that it needs to bribe people to join.
People don't need to be bribed to join Reddit, Twitter, YouTube, Facebook...