As far as I know, mold design is a special field and significantly different from common product design.
My personal suggestion is:
Follow the workflow of your veteran colleagues or buddies and try to reach their skill level first. After that, start to think about improvement.
I worked in such different fields as automotive, white goods industries, pet an so on.
It is evident that every works is dealt with the most appropriate ways.
The aquarium or the kitchen, for example, are part of a modular project for which correct parameterization becomes essential.
The air box is completed by the tool maker with the addition of drafts and blends. This work does not require particular parameterization.
I understand your disorientation but no parametric native file are provided very often.
I provide tool maker with completely drafted and blended parts, the work of the tool maker should (must) be to make the mold and not to fix the part.
i have a very similiar case XD
did you tryed to explain how "your method" works within NX ? the people do the way they are guaranted to work if they never used/ when they used it, it caused prroblems they turn around imidiatly .
i blame the sales representetives in how nx is distribucted and taught to people. people pay an exorbit amount of money for licences and support and only licences renew its whats we are truly benefiting , a lot of times they told me "go to help and search" in a call for support.
sketch is a way tru def. but rememberr 3d its also very good in a lot of situations. (in my case im mixing the 2: sketching and 3d modeling depending on the situation)
you can start on customizing your mold librarys with sketchs