Damaged, weak or overgrown hooves can mean your horse will probably go lame, and you’ll have no horse to ride or drive. This is as true now as it ever was, and why good hoof care is essential.
Without healthy hooves, your horse won't be very useful or happy.

Even in ancient times, good horsemen realized that what makes a good horse is not the cost of the equipment, but understood that the key to success was patient training and consistent handling. We’ve all seen ‘golden bits’ advertised; the ones that promise to make your horse perfect because they do this or that wonderful thing. And many of us have seen riders that jump from one bit to another in hopes that it will solve some problem.
Chances are a bit, or any other piece of equipment is not going to solve a problem. When problems occur, the first question of the many we should ask is why? There are similar quotes like, “You can not judge of the horse by the harness,” nor the rider by his clothes. Good horses and horsemanship have little to do with the trappings.

While we value horses now as companions, they were once valued as modes of transport. You probably wouldn't give away a young horse that was still useful. When a horse got old, it would no longer be able to pull or carry loads, and therefore, had little value. One way to tell if a horse was old was to open its mouth and look at its teeth, which would reveal its age.
So, don't look in a 'gift horse's' mouth, because you'll probably find out it's old, and you'd realize you had gotten something of little value (and not appreciate the thought behind the gift - if indeed it was well intentioned.) Pity the poor horse whose new owner followed this axiom.

... three white feet, look well about him; four white feet, go without him.
This saying has variations such as ‘four white feet and white on his nose, take off his hide and feed him to the crows.’ That’s pretty harsh! Or, one, buy me, Two, try me, Three, shy me, Four, fly me. This old saying is probably based on the belief that white hooves are weaker than dark and your white-footed horse is prone to unsoundness due to wear and cracks.
The saying is reversed in one version. One white foot, keep him not a day, Two white feet, send him far away, Three white feet, sell him to a friend, Four white feet, keep him to the end. Whatever the intent behind the rhyme, we’ve learned that hoof color is not as important as we once thought it was.