I've been working with Qlik Sense for almost 2 years now and this one would save me so much time... I would love to be able to select the number formatting for a measure in the master items. Nothing is more annoying than having to manually change the number formatting each time after adding a master item.
It shouldn't replace the option to change number formatting in visualisations, but there should be a default in the master item that can be changed for each visualisation accordingly.