wp-settings and magic quotes?

Could some one explain to me (in words of one syllable please, I’m not very knowledgeable) what the purpose of lines 459 to 463 in wp-settings.php is?

The section is headed ‘Escape with wpdb’ and it adds magic quotes to the $_GET, $_POST, $_COOKIE, and $_SERVER variables.

More particulalry, I’d like to know what the likely effect of commenting those lines out is likely to be (which I need to do, at the moment, to get the TDO Mini-Forms Plugin to work properly).

It doesn’t seem to break anything, but what sort of risk am I running, and of what?

Is there a WP/PHP guru who can help?

TIA