passing is a primary skill for (point) guards, if not even THE primary skill for them.
The reason why many NT guards don't have high passing is twofold. On the one hand, they have been trained in the past, when passing was less important than it is now. Also, high passing will lead a PG to hit the potential cap earlier, and that is of course unfortunate. But for your own PG, you should definitely go for passing in the range of your other main skills. NT needs are not the same as team needs in most of the cases.