One of the things that makes the Android OS so successful is that users have the ability to sideload any apps that they want so they aren't limited to what's in the Android Market.  However, AT&T has removed this option from all of its Android phones.  We've never know why they do this, until today.  The carrier has set up a page on its site, seen here, dedicated to showing off Android and its features.  In an Android FAQ on the page, we see the question "Q. Why can't apps be installed from sources outside of the Android Market?"  The answer?

A. Android Market, managed by Google, is open to all developers. There is no approval process for applications, they are all accepted by default and Google has stated that they place apps in the Android Market within 24 hours of their submission. AT&T selected Android Market as the exclusive source for applications because it forces developers to be accountable for the apps they submit. If the Android community has issues with an app, the app can be flagged and removed. This minimizes the risk of malicious apps harming customers and provides more protection to the customer’s private data stored on the phone.

AT&T's explanation actually makes some sense.  The carrier acknowledges that all apps are accepted and placed into the Market within 24 hours.  Because of this, developers must be accountable for the apps they submit.  If there are any problems with the app, the community can have it removed.  This way, the Market polices itself and protects user data stored on the phone.  It's kind of surprising to get such a straightforward, reasonable explanation from AT&T on the issue.  We may not like what they're doing with Android, but at least they're being straight with us.

Via Android Guys