although not all of IEO cares about bounties
I think i have not seen an ieo that do not care about bounties, why ? Because every project needs good marketing, irrespective of whatever product you have, it won't thrive without marketing.
Bounty marketing will come in form of airdrop campaigns, or bounty campaigns and it will continue to remain for a long time.
The reward and good projects may be less, but bounty have a permanent place in the crypto world in my opinion.