Bounty campaign is one of many ways to marketing the project and i think every new project need marketing. A lot IEOs project held bounty campaign and i think its good to success because i am believe bounty hunters help the project reach the target
not all IEOs give permission for bounty campaigns. such as binance which provides a project ban on bounty activities during the IEO. but if the IEO is done in another exchange I don't think there is a problem with that.