Not at all, it is simply that you can transfer it to a laptop or between systems at any time.
Technically, "installing" it is as simple as adding it to the PATH.
Now, why would all that be good?
Maybe because then you have nothing to uninstall, no program conflicts, you can have any number of duplicate versions, it doesn't mess up the registry, nor does it contribute to DLL hell.
Many IDEs *use* it, but at that point, you have to choose an IDE for yourself, and simply suggesting one is worthless.
Have you ever had to move systems, for example temporarily to a laptop, or between computer upgrades? If so, does your compiler need to run an installer just to work once again?
Countless free games do not use installers. Does that mean that XCOPY deployment is a sign of playing games at work? Certainly not. It is a sign of not having external dependancies, that you don't have to keep an installer and uninstaller handy just in case you need to move between computers.
It means that you can take it with you to a friend's house on a portable storage device and not have to worry about installing anything on their computer.
XCOPY deployment is the essence of flexibility and elegance.
Also, since you seem to care so much, look at the security model of linux, and likely many other computers: Even on an administrator account, you don't get administrator priveleges without specifically requesting them, as it prevents the spread of viruses to system-critical files. In fact, how can you possibly encourage the use of any version of internet explorer at all, if it only runs on systems with an inherent security hole whereby an administrator can run anything they want without excessive authorization to ensure that, yes, you *do* want to adjust advanced security settings or upgrade software.