I like having the miniames unlocked and playable as soon as you have played the once on the boards. It just seems like I have to do more work just to play a few minigames.
I liked the idea of buying minigames, but I qould rather use the coins to but good stuff, like that Bowser Scroll from MP1 or something more improtant.
Coins was a fine addition and now it's not used much. Using coins to buy things was neat, but served no purpose outside of board play after Mario Party 3.
I mixed with buying minigames. Cool if you just want the favorite ones. But it is annoying cause you need to keep playing the Boards to get more and buy more.
There's other variations of this like the stars in MP6 or the card points in MP7 so at least the idea never escaped. I actually liked the star bank from MP6 better. But the coin thing is pretty cool nonetheless.