I create a hole, a distance from a pair of datum planes. I type in the values for these distances. I change the location of the hole, perhaps I create a new datum plane. I remove the old datum plane - the typed-in distance to that old datum plane disappears. OK, I can kind of see that, but why does the typed-in distance to the other datum plane (which I have not changed at all) change to some random number? Surely it would be common sense to assume that the hole is at the original distances away from the replaced datum planes. I typed these numbers in for a reason. What is worse, there is no indication that the second number has been changed at all, so, unless I specifically check, I may not know it has changed.
I create an axis normal to a plane and through a point. I want to change the point, so I remove the point reference and point to another one. No problem, until I notice that the 'Normal' constraint has mysteriously changed to 'Through'. Again, I chose 'Normal for a reason.
There are others. These are just a representative sample.