Weatherpack plugs are overkill for the interior.
Weatherpacks are designed for exterior use to prevent water and moisture from entering the connection.
This is the reason why they have rubber plugs in them.
Almost every connector in your engine bay is like this.
Hell, I guess it doesn't hurt to do this for the interior, but I think it's a waste of time and money.
Are you trying to build an electrical harness that'll outlast the chassis and your life?
Personally, I prefer Deustch stuff.
The plugs are a lot more lower profile than the Weatherpack crap.
You have the option of using machined pins (more expensive) or stamped and rolled pins (on a budget).
Only caveat is that the crimper can be big bucks for the machined pins.
There is nothing wrong with a crimped connection.
A crimped connection can be just as good, and sometimes better, than a soldered connection.
Soldered connections have a disadvantage in the automotive environment as they can fail due to vibration and moisture - this is where a properly crimped connection is superior.
-Ted