"But why is it shying away from using one standard setting per part file?"
I don't understand this question. Part settings only have a single value; only one preference value can be used at a time. Changing a part specific preference will have no effect on existing dimensions; this is as it should be - there can be good reasons to make one or more dimensions different than the others (tolerances, line & arrow settings, etc).
For a sake of one or two rarely special dimensions, why do you want stop updating dynamically to a common scheme applied to the whole part according to one standard values (on existing and also new dimensions, annotations, tolerances etc.)? Under International Standards, those values are set and specified already.
I know in other CAD software, when you switch your standards, those standard specifications are applied instantly. If you change the standard values to your likings, it will show that the system is following modified standards. Eg. DIN-modified. If you really want to change some few instances, it allows to change them individually. Whatever it is, it corresponds lively, not like NX sleep mode which needs re-energize repeatedly, giving a boring and dead feeling.