What is the difference between enabling people to download files by passing commands directly to MIRC, or enabling them to download the same files via some kind of clickable link?

Because, as demonstrated by Kingtomato, this function (which has been suggested before) can be used for bad things - really bad things. The fact that this forum (and actually most forums) allow this feature doesn't exactly lend me much comfort, though the fact that we have a regular moderator presence makes up for this. On IRC the story is alot different, if you go into a channel where the hosts are bots and not real people and someone posts a "link" to the channel where the keyword is just anything generic, how does the bot realise if this is advertising of a dangerous website or not? At present a bot can detect "http" and ".net" or whatever and ban the luser that posted it. The ban would be an indication to the other people in the room that there is a possibility of the URL leading to a dangerous site.

The idea is convenient and by itself there is nothing wrong with it, but it is very easily taken advantage of by the underground elements of the Internet.

Because the idea would not be supported 'server-side' there would surely also have to be integration with all other chat programmes, an unlikely scenario.