While showers are a gift, and you are supposed to sort of take a backseat in planning, I don't think you're being unreasonable, given that you are thinking of the guests and not yourself. Just have a plan for if/when your hostesses see the invites and they ask you why none of their great ideas were mentioned on there. If you truly are very uncomfortable with those plans, and I would be, given how much "extra stuff" it imposes on the guests to bring, I would buck up and say, "I just really wasn't comfortable with those activities and prefer to leave them out, so I didn't include them." If not, you may run the risk of having it pass to your guests word of mouth (if you hostesses think you just 'forgot' to put it on there), and having to deal with that whole issue.