It would be important to have an option within the editor to set prefilled values on multi-select option sets.
In our scenario there is a multi-select option set named "interested in" which shows different products from different business units to show which lead is interested in which topics.
As we have different forms for every product we hide this field and want to give a prefilled value. In the HTML the prefill value can be set, but when we do it in the editor it is not saved. Pretty sure due to limitations of the field type. As it is possible in HTML, it should be possible to bring the correct setting in the designer.
As the creators of the forms are not into HTML, CSS etc. it is important that they don't use the HTML Editor, but can do easy settings like this in the Editor on there own.