I think when it comes to game balance people just need to accept what category of player they fall in...

Cash player vs. Free player
AND
Grinder vs. Casual

1) Cash player + Grinder: You're gonna rank in the top and get most of the cards.
2) Cash player + Casual: You have an easier time accomplishing rank / achievement awards when you feel like playing, but don't expect to get everything.
3) Free player + Grinder: You are going to be tied to your computer to do focus/stamina dumps every 30min when you're not at work/sleeping. You will probably get most achievement awards, but even with grinding some rank awards are going to be tough.
4) Free player + Casual: You should be content with Explore/Story cards.

Grinding can make up a bit for not spending cash, but you won't be able to compete with cash players overall. I managed to open plenty of pink cases during the last gambit event but it was a HUGE time sink sitting in front of the computer. Now I'm exhausting all my consumables trying to keep up with this event and come the next event there is very little chance of me ranking. You just need to pick and choose where you want to be successful. But if you're not willing to grind or spend money then you're basically a casual player and should expect to get the awards a casual player would.