That is a very good point! I am also in it for the long haul. But from the online chatter, I think most people signing up in the last few months, are doing so for more immediate rewards - while they appreciate the increase in Steem Power little though it might be.
In any case until SP goes up significantly, it does not have an big impact on curation rewards or the ability to get noticed. On the other hand, someone who is not interested in using the cash can always turn the SBD into Steem and use it as Steem Power.