I have seen many webpages attempt to secure their information by disabling the right click. Not only is this a bad practice, but limits your users in function that they would normally do.

First off, why is this bad? It is bad because it is very ineffective. Lets list the reasons.
It uses Javascript.
Any web savvy web user knows that javascript can be disabled. If they really wanted your content they can just disable javascript and bypass your script.
Print Screen
If they wanted your images, all they would have to do is do a screenshot and they have your image.
Menu - View Source
If you are trying to prevent them from gaining access to your code it isn't going to work. All browsers have an options to view the source from their menu systems. This gives them access to all your code and by consequence the URL's to all your images. Some browsers (Firefox, Safari, Chrome) have extensions that enable the visitor to see all your source code without the browser menu system so that is another way for them bypass your script
Takes time to load
Because it is a script, that means the browser needs to execute it. This takes time and browser resources which will make your site just that much slower.
User alerts
When a user does right click, they are alerted by a popup that the function has been disabled often requiring the user to accept the notification. This added click will do nothing but annoy the user who will often times just leave your site never to return.
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Now the title said that it disables your users. How could the right click be a plus for users?
New Window or Tab
All browsers have the ability to open up tabs in one window. There are many users that use this functionality and a popular method is to open up links via the right click in a new tab or window. If you disable the right click it will make that method all the more harder to do.
Bookmarks
If the user wanted to bookmark the page via the right click menu, this would no longer be possible. The user would have to resort to the menu system. And unless you have really good content, they probably are not going to bother.
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So you don't want people to steal your content, so what can you do?
Watermarks on images
Seems simple enough. It is a good start but be warned that even this is not fool proof. A poor watermark can be removed with an image editor.
Don't put it on the internet.
If you absolutely don't want certain content stolen just don't put it on the internet. It is 100% fool proof.