In the custom maps (made by fans of the games), why do so many of the creators think it's fun to have an area in the game where an alarm goes off, and hordes of infected run at you in such large waves that you can walk one step, then have to hit and hit for 20 seconds (using the katana of course:p) to kill them so you can move /one/ more step and repeat the process?

It's not very hard to get through, but it's so boring! They might as well have put up a huge brick wall and have me hack my way through it instead, and have it take 20 minutes to get through it. That's how much fun it is to run through those hordes.