I think it is considered rude to the horse if not grooming them after a ride. It's like, disrespectful. They gave you a ride, they put up with you, they did all the hard work as far as muscles go. You will have a stronger bond with them if you do. My old freind said, "A horse will treat you, how you treat him."
I always brush him, then, I rub his heart girth on both sides where the girth was to get circulation and comfort and I do the same to the sides of his lips where the bit was. He loves this and starts to lick his lips. Other horses aren't too fond of it, but it does help. To me, not grooming them like that, is like not taking care of the horse....
But before saddling is always a must! Everyone knows mud or grass can itch, bother, or poke the horse with a blanket and saddle on.
Lettin' the cat outta the bag is a whole lot easier than puttin' it back. -- Unkown