I wonder if her apparent disdain for dressing up all the time is in part due to her noble background. I often read that people in the UK who have aristocratic roots/titles stretching back centuries are the ones with the messy houses, sloppy clothes, older vehicles, etc. because they have nothing to prove, whereas the more nouveau riche wealthy are the ones who are more consumed with appearances, labels, etc. Of course that may not even be true for Britain, but I do wonder if it may be kind of true across the board.
I get what you say but the problem with Steph isn't that she's not fashionable, rather that many times she seems totally unkempt.
Thank God now she shows genuine interest for her engagements and duties, because it does make a tone of diferrence but there are details she needs to take under consideration.
Detail here, detail there and her whole image is not suitable for a hereditary grand duchess. She wants to carry big scarves and wear wide pants? Fine by me but the scarves should be ironed and maybe come with a decorative brooch to keep them in place and add some style. As for the pants, they need to be in the proper length.
She's much better since little Charles was born, so I believe she'll find her way in general. She has the resources and she represents a nation, so she has no excuse not to try. That goes for any royal with duties and an active title.
Showing off and having a proper public image are two diferrent things.