I totally agree with this. We need more ways to earn, not less. 
I look at the current credit earning system as a good way to balance things between people who have more time/less skill and those that have little time/more skill.
It obviously doesn't help those that have little time OR skill, but like I said, that's motivation to get better.
For someone like me who has little time to devote to the game but can earn more credits in Fireworks after a few games than I could after an hour of clams, it balances the playing field for me. Otherwise it would be impossible to catch up to someone who has several hours a day to devote to clamming.
***It's certainly easier to improve your skill with a game than to find an extra few hours in your day.