DB Vista is one of the most under-utilized features of Adobe Analytics because it requires working through Adobe's Engineering Services. I would like to see a version of DB Vista that is available to administrators as a self-service instead. Just as Data Feeds used to require Engineering Services, but now is self-service, so too could DB Vista. I have found that Data Feeds is used much more now that it is more accessible. I think the same would be true for DB Vista.
I also think that this would help enable this tangentially related idea: relational data for processing rules