Contact pages on websites are made up of a bunch of fields, basic contact pages consist of the Name, Email and Comments fields. This html page is nothing more than a form that gathers information, it requires a PHP script made up of various strings to gather the information from the contact page and forward them to an email of your choosing. The contact page gathers the information but it is the PHP script that houses the information on where to send the gathered information such as your personal email address.
The above set up makes your website look professional and also keeps your email hidden away from possible spamming bots.
Although the above is true there are still some advantages from having a mailto link, some have reported their host provider does not support PHP script on their servers for your contact page, therefore to ensure you provide the visitors to your website the opportunity to contact you, a mailto link will offer this.
Another positive from offering a mailto link is there are still a lot of people who do not like filling out their personal information onto a form, on what might be a website they have visited for the first time. A mailto link when clicked will automatically launch the visitors email application; here they will be more comfortable sending you an email.