The issue is server load... if people could search for certain small strings, they'd get half the posts on the board as results...
The search is one of the most server-intensive features of the board, so I want it to be limited.
The keyword length limit is an idea stolen from other forum search scripts.
Perhaps we should have a big list of useful/popular threads, all organized into categories, all on one page. The user could scroll through, or do a Ctrl+F, to find what they want. Anything they can't find on the list could be searched for. It would be "cleaner" than having tons of sticky threads. 4 stickies per forum is like the maximum, IMO.