I support your request. I know EasyMorph is a graphical ETL-tool and I know that powershell scripting is supported but for data manipulation that fall outside the scope of the actions I think support for R/python would be a nice feature. Some other ETL-tools also support this.
Some more flexibility in some actions would be interesting as well like run an action based on a condition. Now we can only skip all actions in a table after the skip actions action. It would be nice if we could do this at the level of an individual action as well.
Other improvements: be able to perform operations on a bunch of columns without the explicit use of iterations or unpivoting. Be able to upload download actions from e.g. sharepoint, S3 using wildcards, etc.