Looking at the plate, two possible answers come to mind.
The less likely one is that from the MAP you have 0.2 miles to lose 674 or 1084 feet depending on category, making an impractical descent angle; however since they also publish advisory heights for a 3 degree approach I think this is unlikely.
A more likely reason is the fact, that is not terribly obvious from the profile, that the VOR is actually 5 miles beyond the runway. Therefore the "cone" of possible position at MAP is probably too wide for a straight in approach to be guaranteed, so they have assumed that you will have to do a circle to line up with the runway.
It is very easy in these days of FMS/GPS overlay approaches to forget just how "non-precision" the traditional aids are!