Yes, we must be careful to use it sparingly and only in the extreme cases that could result in many negative reviews.
A real world example of how this can ruin your rating:
I use a text editor on OS X called 'Mellel'[1], which is available both in Mac App Store and as a direct purchase. It's excellent and supports RTL languages (Persian, in my case) better than any other text editor. There was a bug on OS X 10.7.4 that caused the cursor to disappear. It was a simple bug and the developers issued a notification to all non-App Store customers (they obviously have their emails) on how to remedy this issue, but it took them like 10 days to update the app on MAS, causing a few negative reviews.
A real world example of how this can ruin your rating:
I use a text editor on OS X called 'Mellel'[1], which is available both in Mac App Store and as a direct purchase. It's excellent and supports RTL languages (Persian, in my case) better than any other text editor. There was a bug on OS X 10.7.4 that caused the cursor to disappear. It was a simple bug and the developers issued a notification to all non-App Store customers (they obviously have their emails) on how to remedy this issue, but it took them like 10 days to update the app on MAS, causing a few negative reviews.
[1]: http://itunes.apple.com/us/app/mellel/id415467848?mt=12