In the DS version of Animal Crossing, if you don't water your flowers they die. If you ask me, being forced to do it doesn't make watering things any more fun. But some people really enjoy running around their towns with a watering can- they enjoy the having a tangible goal. I think both are valid approaches to playing.
I agree. But
1) being forced is difficult to make optional (solution could be to have both "forced" activities and optional ones; or perhaps an "easy mode")
2) sometimes the choice of forcing the player or not is directly related to the expression (e.g. in our mmo The Endless Forest the optionality to do things is directly related to the feeling of joy we want to express, while in our The Graveyard, forcing the player to walk slowly in turn helps express what we wanted to say with that game); so it can be an artistic choice as well.