When trees grow in diameter the older (and outer) bark can not stretch to cover the increased girth. As a consequence the outer bark cracks. The shape and pattern of these cracks are genetically controlled and do not indicate any inherited weakness.
There is huge variation in bark appearance among pecan trees. Growing behind my office are three seeding trees, all the same age and roughly the same diameter. All three trees are in perfect health. Bark appearance among these trees ranges from furrowed to shaggy (Photos below).