It’s similar to a request to do it on iPad I made: http://illustrator.uservoice.com/forums/931888/suggestions/46244521

Ditto.
Ai should give us a mode to freely rotate the bounding box the way we need, to zero or any angle.
There should be a way to quickly align it to a chosen straight segment or even a point.

Affinity Designer has a feature that can be used for this purpose, Select > Cycle / Set Selection Box — even though it doesn’t exactly does the same thing.
There are also two plugin methods to achieve this in Ai today:
1. ToolShed plugin by Graffix: https://rj-graffix.com/product/toolshed/ (it introduces a separate tool for transforming, to avoid dealing with Ai’s bugged accumulated rotation — the tool allows to 'visually set the bounding box angle in order to stretch the art along any angle you choose')
2. Bounding Box Tool by Totallypic: https://totallypic.com/digital-downloads/categories/plugins (not sure though it’s still available separately now, the developer intended to include it in their larger IllustKit plugin)