Here is the wording on my Party Bonus card...
If someone has the Party on the table, all players may Draw 1 extra card and may Play 1 extra card during their turns.
It's the word "may" that's throwing me off. With most of the other new rule cards that I've looked at, the description is very clear that you must do what it says. In this case, however, it seems to be left open to the player's discretion.
EDIT I guess the other part that throws me off is that I read through all of the new rule cards and found that the Rich Bonus and Poor Bonus are inconsistent on the same subject. Only the Rich Bonus one says "may." The Poor Bonus is worded as though it's mandatory.