How do you feel about privacy fences?

Wife and i have lived 40 years in the same paid-for home. new neighbors have moved in to one side and behind us. both neighbors are very nice people. each one wants to install privacy fences and each asked if this was okay with us. they did not have to do this, by law. i appreciated their upfront respect for us. wife and i totally agreed with both neighbors that its their property and to do as they wish. i have had an afterthought: did the new neighbors have something to hide or is their privacy really that important to them?