I've never had a problem with tripping. It has happened to me a couple times though, but there's no pattern or trigger to it (with the possible exception of running/dashing for a long time, but I've had it happen when I was walking and sliding too). I'd call it random. I agree with the theory that it was probably put in to randomly screw up people who bluff dash. It's agreeable. It potentially screws my opponent as much as it does me, with a luck factor thrown in for good measure.
It's realistic. You can pull off a pro flawlessly some of the time, but you can't pull off a pro flawlessly all the time, even when you think you can. Sometimes you screw up and trip.