Why we don't recommend installing extensions via Magento Connect

Please note we don't recommend installing extensions via Magento Connect for several reasons:

• Installing an extension with the same key at different times could install a newer version of the extension (which you did not test in your test environment) 
• Getting server file permissions right can be complex, and too many people resort to giving unsafe read/write/execute permissions to everyone (777) to get Magento Connect Downloader to work 
• The extension is downloaded and executed in one step, without giving you a chance to inspect the code first. Unfortunately not all extension developers are trustworthy
• Occasionally, installing an extension with Magento Connect Manager can trigger an upgrade of the Magento core itself (which you might not be prepared for!)