Obviously, many other operating systems and windowing programs offer these types of programs. But if you do have a compelling reason to use X, you may as well make use of the other benefits. Every client-server system has to consider network security, and X is no exception. This is not an idle question. It is quite possible while using X to inadvertently let others read and write on your screen, including reading passwords you thought were hidden.
X provides two security mechanisms.
One, the xhost mechanism, is easy to use and, unfortunately, easier to abuse. The other is the magic cookie mechanism. It's a bit harder to use than xhost, but provides much better security when you run your X clients on a multi-user system. Neither, however, provides any real defense against network sniffing. Yes, the people who use tigger happen to be a nice, friendly bunch, but you can see that this could pose a problem.