@Anser
Mario Party 8 does have several major flaws, which you indeed pointed it out, but I think Mario Party 9 is worse for ditching several characters

toadette

, and adding in random playable enemies. I don't really play repeats of the minigames three times, so I think it's a bit of an exaggerated claim. Mario Party 8 does have bad/unresponsive motion controls, but it's still functional (if you want the pinnacle of bad motion controls, consult
Sonic Free Riders. :/) I also agree that the taunt is highly sensitive, but I tend to spam the taunt anyway, so I guess it tires my arm.
Mario Party 8 is incredibly luck-based compared to Mario Party 2-8. Donkey Kong and Lucky Spaces... those are the bane of my existences. Goomba's Booty Boardwalk and King Boo's Hideout (whatever) also rely on luck. The stars in the boardwalk are essentially
free and the game HAD to put a ? Space that punishes you severely near the end of the the board.
Judging Mario Party 8 as a single player game (no replay value! LOL!) is unfair, and Mario Party 8 is supposed to be played multiple times, with friends. But the requirements to unlock both characters are ridiculous. Story Mode, still, is just a side-thing, with Party Mode still being the main focus.
Mario Party 9, on the other hand, detracts even more from the formula. They remove an entire category of minigames and ditched Tag Team Battle. Tag Team Battle is the sole reason my sister and I play Mario Party because... well... it's fun! But no, they had to make winning hugely luck-based, with devastating events happening near the end of the game. Not to mention, the mini-games and battle minigames rewarded winners hardly anything. In the end, it is entirely possible to beat a game in Mario Party 9
blindfolded. You can technically do this via Fortune Spaces (swapping Stars near the end of a game), but the chances of this are barely feasible. Mario Party 9, however, isn't the same.
Saying the roster in Mario Party 8 is bad because of some characters can be okay, but Mario Party 9 and Island Tour had the most barren rosters of a recent Mario Party game; Mario Party 8's roster at least refrained from cutting any character from Mario Party 7. Saying that 9 and Island Tour's rosters are better because some characters AREN'T playable is selfish.
Mario Party 8 is one of the worse Mario Party games, but I still had more fun with it than playing Galaxy 2. </bad tastes>