Yes em I have already raised this issue.
But you asked "Why not locate them on ground that hasn't too many people around, or any people for that matter".
Well get ready you won't believe this, I heard on the radio that they did consider locating them in an area of natural beauty that being an area were a particular rare species of wild plant grows, but they decided against this place so as to protect this plant.
That's typically English, we would rather protect a wild plant, but are not bothered about placing these high explosive devices on top of the heads of humans.
And has anyone considered the implications if they have to use these missiles in a crowded city such as London? Not a particular threat to the tower block residents, but lethal to those a few miles away living underneath the fall-out of these devices.
Then of course if a high-jacked airliner with passengers on board happened to enter our air space what then, would they shoot it down over a crowded city?