As a new dyer, the first thing you are told in class is to avoid white patches - don't tie your skeins too tight, make sure the dye covers both sides of the skein, rub the colour in etc. But why should we be so cautious to cover up the white? I mean, it's not exactly white - it's more a lovely creamy, milky natural colour. And I, for one, think it's far too beautiful to cover up.
Some of my most popular colourways - such as Team Rainbow - utilise the white space to counterbalance the WOWBRIGHT of the rainbow colours, whereas others, such as Cotton Candy use it to facilitate a blend between the two main colours.
It can be difficult to retain the natural colour - as dye can run, but if you are careful with exhausting the dye bath and with how to wrap the skein before heating then it should be fine.
I love seeing natural wool colour shine through, and it's wonderful to see the colours that different wools are. Wool is beautiful, and I don't see why it can't be just as desirable as the bright colours that dye can achieve!