This is the best classic construction method, which allows for re-soling and thus increases the shoe's longevity. Additionally; well-worn leather shoes have adjusted to the shape of the foot and are more comfortable.
The stitches seam on a Goodyear welted shoe, which is visible from the start in such an open-channeled stitch.
This Crockett & Jones oak bark sole has a closed-channel stitching, i.e. originally the stitch is covered by the outer layer of the leather sole, but with time this superficial layer wears off and the stitch becomes visible gradually - this is normal and not a defect in the sole.