Add fine-grained controls, stats, and monitoring for played ads
Allow streamers to control which ads play to their viewers.
Best would be to allow pre-selecting ad-categories (similar to what advertisers use on e.g. AdSense to target their audience) to filter specific ads from the channel.
AND also add an archive of played ads (in the best case together with ads of how many of the audience members have seen it (by now); how many viewers left while it played; how many reported it; and such) and allow to verify it if viewers complained in chat about an inappropriate ads to either manually blacklist it for the channel to never be played out again to the viewers; an option to never play anything from that specific advertiser again; as well as an option to report it to twitch for further investigation if it was not just "channel inappropriate" but violated TOS or local law.