from my guess the crossword was only to unlock the handful of scenarios but after unlocking them all there is no point on continuing. I would think it's because more scenarios haven't been implemented yet. Also im guessing the cards were the original idea for the game then the creator chose to switch the core game mechanics. I personally prefer the second parts game mechanics over the cards but thats just me.
That's right, once all the words have been discovered there's no point in going back to the crossword. There were supposed to be more, but in the end I chose to update all the old cards when we LVL up rather than create new ones that we'd have to go and find, for the sake of comfort. I understand that it does give a feeling of "lack" though!
As for the change of mini-games, these change with each chapter. With Chapter 3 just around the corner, the current job phase should in turn give way to a new interactive experience with the girls.