I understand that Tab icons can be helpful from a UI perspective, to make it easier to navigate around a number of different types of records in the sidebar etc.
However, for my use case (a custom object, custom tab, custom controller and VF page with enhancedList property showing a list of the object records created), I don't want to have a custom tab because it seems like extra 'noise' and the existing icons all look 'cartoonish'. I had tried creating my own logo with the text of the object, but due to pixelation it looked awful. I haven't tried yet with a .SVG file though.
It seems that the icon is indeed a mandatory field. Short of creating and uploading an 'icon' that literally just has a white background, is there a way around this?