My problem is what you need to spend money for, meaning Content. By Content I mean Cards. For example the first part of the last event was fine. You could reach the videos and the card without need to spend money, and if you went further you got a lot of cool stuff, that helped you along.
Making life easier for paying player is just fine, boosts upgrades, etc. What gives me a bad taste in the mouth that some part of the game, namely some cards are not available for non-paying people, no matter how much time and effort they put into the game.
For me successfully completing the event means to get the new cards, but I am destined to fail, as I won't throw a bunch of money into the game. Sure I get a lot of stuff that boost the lvl of my cards, and SED, but I still have a feeling of failure.

Sorry for the rant, I just wanted to share how I see things.