IMO you are being overly concerned. Hooves look hard and dry like the weather has been dry of late and this is a normal hoof. What does your farrier say? I see nothing.. just new growth of hoof wall at the coronary band and then normal hoof horn below it.
Take a stiff brush and a bucket was soapy water. Scrub the feet off and I expect most of what you are seeing is dirt, older, tough, dry horn, and a normal hoof. They look a bit dry and if you have not had rain, then you are seeing the results of that.
If you want to you can buy something like "rain maker" and put that on the feet or just use some vaseline. Clean and dry the hooves first (as noted above) and then coat them with vaseline to seal moisture IN the hoof.
You can also supplement his diet with something like Mirra Coat or a little bit of fortified wheat germ oil. This helps skin and hooves and can make the shedding a bit more uniform and the coat shine.
How long have you owned a horse?