When it comes to your personal computer, you probably constantly get reminders about updates. Some proprietary and open source web applications will also remind you when it is time to update, but website still suffer from attacks that stem from the failure to consistently keep their apps updated.
In most situations, a software vendor or developer will release an update to either fix a bug or to patch a security hole. If it is for the latter, any website that continues to use that software without updating is vulnerable to attacks, especially after those vulnerabilities have been discovered and made public.
Therefore, the short answer to the question in the title is that web applications updates are very important. Whether you are running a small script or a robust content management system (CMS), making sure you have the latest and most secure version could save your website from disaster.
Some web apps, such as WordPress, are very easy to update, while others may require reinstallation. If you know ahead of time that keeping your scripts updated will be too much for you to handle, you should consider using a web hosting provider that offers free script installation technology. These services are usually integrated into the host’s web-based control panel.
There is a chance that no one will ever exploit old security holes in your web applications, but failing to keep them updated is a risky move, one that you should not be willing to take with the security of your website in jeopardy. Taking the extra time to update all of your web software could be one of the most important things you do as a web administrator.