I believe the OP is stating that JJPs new pin appears to be better quality parts than Stern, and not that Stern is making poor quality pins. So far, WOZ looks like an amazing pin, quality/innovation wise. Bummer theme though.
To your question, you need both to make a truly great pin. Having only one of those ingredients will result in one of 1000s of pins rarely talked about on Pinside, or sought after for very long.
My prediction: WOZ will be available for sale second hand for $5000 or so for a long, long, time.
As soon as it's not the absolute latest/greatest(?) pin, it's going to be looked at for what it really is:
A horribly themed pin, in a nice wrapper.
We'll all enjoy playing it at a friend's place for a few games at a time, but few will want it taking up valuable pinball real estate in their home, at least with the sound on.
I don't mind being wrong on this. If you've pre-ordered WOZ, I'll keep my fingers crossed for you.
It's better for us all if this turns out to be a masterpiece.

Yeah, you're absolutely right. Not only are they holding their value, but with the exchange rate being what it is, they all seem to have increased in value here in Canada, even after a couple years of being played.
Although the title isn't for everyone, the game still seems very popular with many supporters.

I am glad to be wrong on this as it's just better for everyone if JJP can continue making pinball machines!