The problem with the App Store, is that the software most likely to have an issue with the sandboxing is often the software that's more critical in terms of security. Such software may not be security software but still have more stringent needs in terms of security review. For example, layout managers might have hotkey functionality that could disguise key-logging.

Just because you never had a problem doesn't mean you never will. Past performance is no guarantee of future results, and in fact it would be trivial to get a malware-infected app into the app store because the review process does not look at the source code (and even if it did it's not hard to obfuscate malware).

yeah very good argument. you never install anything from the command line or what?