Hi Gustav ,
You're opening a can of worms here .
In recent UX circles of those in the know I notice the word "design" is being used more frequently than the word "UX".
It is thus becoming a question of what was 1st scenario , chicken or egg , UX or Design .
My opinion - is that before you enter the UX realm you will need to understand the concept of design thinking - relax about this , we were all coded to understand "design".
This brings us to your question - why produce or present something that doesn't look good .
If the visual experience is bad all is bad . It's like getting married in your sweat suit , if you look good you are halfway there.
You need to employ a UX Designer - they ensure that all is mixed and matched before it goes out . Don't spoil your hard work with bad visuals . I know this from experience on being on the receiving end - we turn all bad visuals away, regardless how cool the rest is.
Join the Interaction Design Foundation (IDF) in Copenhagen , this will sort you out.