I actually enjoy reading the strips that feature the animals (not that I don't enjoy the other strips), I think they remind me of the Hanna-Barbera cartoons when I was little (and now, I must admit).
Sam is one of my favourite characters in Horace, and I'm sorry to hear that he's been moved to the sidelines. I'd say this about any of the characters I like though, but as time goes on things change, and hopefully new characters will emerge.
The strips where the humans interract with the animals interest me, as they give an imaginary insight into the thoughts of the animals. And as quite a lot of people are frightened of snakes, well, this gives me hope that Sam may return some day.
Another thing: a dose of surreality is good for you... who needs to read about people all the time anyway?