In a previous answerPreviously I sayanswered that a legitimate use for a utility knife might be when you can only afford one knifewhen you can only afford one knife. In the same post I detailundermine my own answer showing how I found no historical evidence suggesting this reason for its conceptionthis.
I would actually go further and say that I personally wouldn't buy a utility knifewonder if I could only afford one kitchen knife. I suspect that many others on this site, like me, would choosewasn't more interested in venting frustration at having a Chef'spoor knife firstthan providing a good answer.
Leaving aside my dubious attempt at an answer, I did in factdid find a good use for my utility knife a while back: when peeling fresh ginger. I alternated between in-the-hands peeling and on-the-cutting-board chopping off of medium sized chunks of root to peel.
My enthusiasm was short-lived as I discovered a technique on this site for peeling ginger with a cheap teaspoon which works wonderfully and I've never gone back to the utility knife method.
Nevertheless, thisThis seems to me both a general and legitimate use for the utility knife.
A good use for the utility knife is when you need to alternate between in-the-hands and on-the-chopping-board use.
A Chef's knife is unwieldy if used for in-the-hands peeling and a pairing knife doesn't have the heft for chopping. A utility knife is just about good enough at both of these operations that you don't have to keep switching knife.
I don't believe I've tried it yet, but it could be ideal for peeling galangal. The skin on galangal is tougher and less paper-like than ginger and I imagine the spoon trick wouldn't work there.
As an aside, one thing I noticed on my return to Stockholm (and thus to my own utility knife) is that knives are not all made alike. The knife that I used in Australia, that provoked this question, felt so uncomfortable in my hand that I was genuinely bewildered at it being a standard piece of kitchen equipment.
My own utility knife is a little shorter and has a few millimeters more clearance for the knuckles which seems to make all the difference. I still only use my utility knife under coercion but it is, at least, capable of being used.