By doing so, Google is ensuring that only extensions that they have approved can be installed on Chrome browsers, thus eliminating the chances of users being infected with malware. Of course this isn’t a guarantee, but it’s a whole sight better than taking a chance with a third-party website, right?
According to Google, “Malware can change how browsers work by silently installing extensions on your machine that do things like inject ads or track your browsing activity. If you notice strange ads, broken web pages or sluggish browsing after installing some new software or plugins, you could be affected.”
Google also notes that extensions installed from third-party websites might be automatically disabled to help facilitate this move. This means that if you have a non-Chrome Web Store extension installed on your Chrome browser, the developer of that extension will have to submit it to the Chrome Web Store before it can be re-enabled or reinstalled for use.