NO.
Naina, adding it to /etc/profile is like giving access to all users to these commands inherently. Well its not that users cant add it themselves. But why would you want a regular user to run a useradd command ( he wouldnt be able to run it anyway unless he has root priveleges). But not only useradd, there are other commands in sbin dir which if possible should be hidden from a normal user. As I said earlier a normal user can always add the sbin to his directory, but if he wants to, let him do it, I suggest you should not do that for him. By adding it in /etc/profile you are doing that for him.
Well that is my way of looking at it. I agree there is nothing that can stop this to be more secure, but when you know that the burglars can break the door and come in your house, you still latch the door in the night, right ?