Kormac and others have indicated that this is not the dilemma you present it as; it seems to me this comes down to philosophy of explicitly granting users privileges vs. a system whereby all users would have the immutable right to mount a filesystem.
Gilles addresses some of the security problems associated with mounting filesystems. I'll retroactively avoid a prologed and tangential discussion about potential technical issues related to this (see comments) but I do think it is fair that untrusted users not have an immutable right to mount hard drives.
The issue with regard to virtual and remote filesystems (or remote filesystems via virtual filesystems, a la FUSE) is less significant, but this does not solve the security question (although FUSE might, and it certainly would solve your problem). It is also important to consider that the data in such filesystems can almost always be accessed without the need for mounting a device, either through file transfer or tools which extract from images without mounting, so a system which does not allow you to mount something does not represent an insurmountable problem with regard to accessing data that you have bizarrely placed in an image file, or (more understandably) want to get from a remote system. If you have a situation where this is not the case, it might be worth while asking:
What is it exactly I am trying to do?
Where am I trying to do it?
If the administration of the system is fair, then #2 explains why #1 is impossible for you. If the administration of the system is not fair, that's politics. The solution to the problem, "My sys admin isn't fair" is not to redesign the OS so that sys admins everywhere cannot restrict users.
The system allows the super user to restrict your activities, either explicitly, or by omission ("We don't provide FUSE", etc). Privileges are one mechanism by way of which this is accomplished. It may not be nice to be told, "You don't need to do this," but if it is true...que sera...you don't need to do this. Use ftp, etc. If it isn't true, you should pester those responsible.
