Hmmm... Are you sure non-members can use it freely? It's controlled by a completely global option, and not usergroup dependant (unless you're SMOD or greater). I'll put it on my very long list of things to do, but will likely to be completed in a year
As for the reason, it is that way so that we do not completely drag the server to a halt. You may not realise this, but the search feature on a forum uses an immense amount of CPU useage, memory useage, PHP useage, and MySQL useage. You are essentially searching for a few words which COULD occur in all of our 180,000+ posts. Even though the terms may not appear, it will check for them anyway.
Now, if some code junkie, who is able to code a very simple script to reload the search page over and over again, the server would literally cave in on itself. So, we set a limit. That way, we never face the horrifics of it
There is method in my madness!
Alcar...