Problem is that games like Machinarium are still just "hunt the live pixel". You have to hope you get close enough to the active object in order to notice it/grab it/operate it. On a larger resolution, this can be quite maddening.
Game Designers: How about making the useable objects more noticeable (like a glimmer or something). Also having the puzzles make sense goes a long way.
Yeah, that's the route we took with Scarlett on the iPhone as well — there's just an icon you can touch to highlight everything of interest. I'm not sure why it hasn't been a standard feature of the genre; maybe some people enjoy pixel-hunting?
Game Designers: How about making the useable objects more noticeable (like a glimmer or something). Also having the puzzles make sense goes a long way.