I mean if they want, it's their time not mine.

They can do as they wish.
But for me, if I watched a movie with an actor and I disliked the film, I wouldn't palm the actor off as being a bad actor, I would keep that door open as there are bound to be better movies from them because as we all know the quality of a movie can be very dependent on the direction and screenplay, despite the actor's ability.

For example I'd feel sorry for a person who would only watch The Tourist and Transcendence and be like "Meh, Johnny Depp is a bad actor, I wont watch anymore of his films". That would be a shame.

You can't judge an actor by a mere two films.

I think you should watch movies you find interesting and not care about the celebrities in them.

Why? If you're not interested, then don't do it. That's like reading a boring book series- what's the point in finishing?