Interesting! How I perceive this:
- Users who care about security will not choose rubbish PIN, regardless if in-app PIN generator will be available or not.
- Users who perceive PIN security as less of a threat, will choose not to use in-app PIN generator to generate their PIN. They might try, but seeing less memorable pin like 9527 might put them off and they will set their own (weak) PIN anyway.
So the trick is - how to get less caring users to use PIN generator? Simply having it there has a low chance to make any impact, right?
Now to give a bit of personal aspect. I use fairly secure pins for all of my cards. PINs to my cards are linked in mysterious way so I can memorize them well, but without knowing the method even getting one PIN doesn’t endanger other cards (security through obscurity, in a good way I think!). Obviously, I keep this method hidden and it’s a bit more advanced than having pins 1234, 2341, 3412. 
Even if there was a PIN generator in the app, I wouldn’t use it because obviously it wouldn’t generate a PIN that matches my PIN-pattern.