Ok I just saw this yesterday so I can weigh in. Last Man on Earth is at least useful to watch for posterity's sake. But even as a stand alone this movie didn't offer much.
I really like Will Smith, but even great actors can't save a movie that is just plain poorly written. The pseudo-survivalism is going to appeal to people who rely on looting rather than preparedness. Where the world magically becomes a free for all just for them.
Right, we all know that's likely.
Secondly, the movie teases about the socio-psychological aspects of the infected. The infected using traps and dogs implies that they have at least some organizational skills to protect themselves. This means there's a whole other side to the story we didn't get to see. If they delved into it more, the movie might be salvagable. The additional comics on the DVD went into it a tad bit more, but not much.
What would I have done different? Christ, where do I start? I didn't get the sleeping in the bathtub thing. I figured it would be explained in the movie but it never was. I would definitely sleep in a bed. My vehicle(s) would be better fortified against the hordes of hungry infected running on the street. I would have shot the dog THEN cried over it's lifeless body if I needed to. I would have captured more than one to put behind plexiglass to better understand their way of "living" if you can call it that.
A boat is a great idea. A houseboat with a lab that has a trapdoor to the water so once you are done with a specimen then you can dispose of them easier. If I weren't working on a cure, I would have traveled more, for sure. I would have secured the libraries to preserve what's left of human knowledge. No need to have homicidal, aggressive zombies destroy precious information that could be used for rebuilding.