I have written to Boden before about this very issue. I find it stops me buying their clothes even though they go up to larger sizes. I never got a response.
For me it's not just they fact they are thin it's how tall they look. I find it really off putting as I can envisage their clothes on any one shorter or curvier.
I think they they should vary the models they use or go for someone a little more 'average' size. I feel that everything else about the way they present themselves is more for family audience so seems very odd to me that they use supermodel style bodies to showcase their clothes.
As a result I buy my daughters clothes but not my own even though they are in my budget and technically would be my size and style. Very frustrating.
I was disappointed they never responded to my email.