Unless there are issues (another break, infection, pt wants it out because it irritates the skin, etc) we rarely take it out. Usually what we take out is ORIF of a femoral neck fx if: the fracture doesn't heal and we have to convert to endohip or total hip, or if the patient had it done years ago and now needs a total joint.
Think of it this way- every incision is pathway for an infection, so if everything is working okay, it may actually be riskier to take it out. Some insurance companies also may not cover it unless medically necessary.
I do not know about other types of hardware, but as a previous posted stated, IM rods are being more frequently removed these days. I had a tibial rod placed and then removed a year later. My surgeon stated that it was my preference, but if I ever broke the leg again, then it could get ugly with the rod in place. The surgery to remove a bent rod is apparenty horrendous and you risk losing that limb. Another issue that my surgeon said they are finding is that if a rod is kept in place for years and years, then the body can start to leach calcium from that limb and then further complications can arise.