I'd love to give developers some money for the games they put a lot of time into making. Plants vs Zombies 2... I'll probably buy a plant to make them receive some of that.
I quit Clash of Clans after I realised there is no way it's even remotely possible to get better at the game by skill. It's purely down to how much money you're willing to throw at it.
• "power ups"
• "plant food"
• the plants themselves
• keys
• stars
All are just methods of juicing money out of the user, and are generally quite time consuming to gain organically. It's a nasty experience given how good the original one was to play while traveling.
The skill comes in choosing which troops to take to battle and the order and placing to deploy them. The best players internalize troop AI making their attacks seem laser guided, while the worst players just spam troops and fail.
Clash of Clans, unlike Candy Crush that alters difficulty based on your spend, seems to me to be extraordinarily effective at getting players to want to spend gems for time, while remaining ethical in that a free player can play the entire game up to max level without spending a dime and remains on a level playing field.