Sorry you feel that way! The rest of the team and I work hard on it as often as we can. But deep populate is not a feature we’ll be adding— Sails and Waterline are opinionated, and I don’t feel that the performance penalty and potential issues are worth it— instead, we recommend using a native SQL query when you need to do a custom join.
Built in support for WHERE subqueries, on the other hand, is on our roadmap. Currently working to finish core MSSQL support first though. Hope that helps!