FWIW, I'm in the same boat.
I can't draw a straight line without making it look ugly, and a VT100 looks OK to me.
My approach to the problem was to recognise my strengths and weaknesses, and not try to pretend I have any design sense.
I have collected a list of designers I trust, and whose styles I know, and then made collaborative agreements with them.
I see my role, as the developer, to implement the designer’s vision as faithfully as possible, while providing the required functionality, within the constraints of the technology available.
If the customer doesn't already have a designer and/or design, then I recommend the designer who I feel is best suited to the job and/or available at the time.