In writer image scaling is proportional by default, and if you want free scaling you need to hold Shift. But in Calc and Impress everything is inversed. I think it is example of unexpected behavior and everywhere scaling should be proportional.
Operating System: All
Version: 188.8.131.52 rc
reproducible with LO 184.108.40.206 (Win 8.1)
I would agree. CALC and IMPRESS should behave as WRITER.
Another trouble: resizing formulas in Writer isn't proportional by default. Maybe not only formulas, some other stuff too. There must be applied proportional resizing by default everywhere!
It was fixed since 4.4