Like I've said before, I (and loads of others judging by this thread) don't need/want a prompt asking me if I meant to do something.
User Account Control isn't trying to second guess every thing you're trying to do. The reason you receive an elevation dialog when you perform a certain task is because that particular operation has requested administrative rights. When you have User Account Control enabled, even when you log in as an administrator, you're running with standard user rights by default.
The reason why, when you log into an administrator account on a system which is running Windows Vista or later, you are running with standard user rights was to change the way in which software developers wrote software. Now that everyone will be running with standard user rights by default, either in the form of using a standard user account or running in Administrator Approval Mode (being logged into an administrator account with User Account Control enabled), developers have to assume they will not have administrator rights by default. This encourages them to write software which works correctly in a standard user environment, and doesn't unnecessary require administrative rights. That is really the primary goal of User Account Control.
As far as the benefits it offers to user's is really going to depend on whether that particular user would like to run as an administrator, or as a standard user. If you want to run as a full blown administrator and have no inclination of using a standard user account, or making the transition, there is a very high chance that User Account Control is going to be annoying to you. If that is the case, you have the choice of disabling it.
However, if you're interested in using a standard user account, or making the switch over to one, User Account Control is a tool which helps you to do so. It helps you to do so primarily due to the elevation dialogs. If you're using a standard user accout, when ever you need to perform an operation which is requesting administrative rights, the 'Over The Shoulder' elevation dialog will appear which will ask to to enter the credentials of an administrator user on the system.
Being able to perform administrative operations from the same user account that you use for your every day tasks is much more convenient that having to switch to a separate administrator account. While when ever you perform administrative operations in an account which is most susceptible to malware, you're introducing a security risk, it is still a lot safer than running with administrative rights all the time.
