I went back and forth on this for several years but never knew anyone that didn't pick out the hooves, but I gave it a try and haven't picked my horses feet (13 of the little darlings) for 7 or 8 years and have never had a problem with lameness. Some horse owners that come here think I'm terrible for not doing it.
It is a decision that should be made by you - you do what feels okay to you.
Just wanted you to know both sides of the story.
http://www.RideNYS.com Adventure Horse Riding in NYS