Well, for one thing, the long end isn't as sharp as a cut end. I've snagged a finger pretty good on those sharp cutoff ends more than once when reaching into an area where I couldn't see real well.
I've also been able to use a small screwdriver to release tywraps and use them again. Can't do that with a cutoff nubbed one.
/ What Is Wrong With People Who Don't Trim Their Zipties?
To cut, or not to cut. That is always the question.
I cut for aesthetic reasons, or clearance/functional reasons. If you don't care how it looks, and don't need it trimmed, why bother? Like Diggin said, I have also cut my hands more than once on cut zip ties, which isn't fun.
/ What Is Wrong With People Who Don't Trim Their Zipties?