One small step for Tableau, one giant leap for data visualisation kind

I’ve had an idea, it came whilst I was travelling across the French and Belgium border on the Eurostar so I need to sense check this. 

Tableau offers the user in Desktop to colour the view in a number of ‘steps’. You can access this by clicking on the Colour panel of the marks card when a measure is active on colour so why not for size?

Obviously there are a few workarounds to create this by binning a measure or grouping a set of dimensions but it doesn’t have that Tableau ease of being able to do it there and then, changing the centre point of the stepping etc. 

I have found a number of times when I would like to use size on a map or scatterplot and Tableau has not computed enough differentiation between them (even when there is to me as a reader). So why not allow for a grouping of sorts but for sizes purpose? 

Has anyone else found this and how else do they get around it? Or, have a critique of my idea?