Apologising in an oblique way for her suntan, like getting one in the first place is Julia's choice.
As with the dress being too tight, or explaining not wearing a brand's shoes when presenting, joking that she is fishing for compliments, it shows that Julia takes comments seriously to heart; and takes her relationship with viewers seriously too. I am glad she does, as it reflects well on her professional standards.
She is not perfect, and is no longer one of my preferred presenters for a number of reasons, however if Julia is on, the show will normally be more good than bad.
The least QVC could do for her and other presenters is to make sure there is a suitably-sized choice of garments to wear for fashion shows. If you work in a clothes shop, you would be provided with your correct size, I believe. So why not at QVC??