Is there any plan steemit would allow advertisement to let content creator to monetize on their content further? I think it will add an extra layer of incentive for people get involved and speed up the adoption. Is it possible to add it to the current model somehow?
Yes, the idea is good, but no one wants to share their profits with ordinary participants. 
Not sure I understand you. Who wouldn't want to share their profits? the platform itself? as long as the platform makes it possible, the content creators could directly get paid cutting the middleman entirely. Though in this case I guess the campaigners will have to pay in steem for per impression/conversion. Which will also reward steem token holders since the demand for token likely to increase.