He is not describing good people. Good people can reason that hurting others is not how to improve mood.
When you say "others" you're implicitly ascribing personhood to those animals.
I'm not arguing whether this is right or wrong, but it's where we are now as a society. In general, most people do what's socially acceptable and avoid doing what's not. It is socially acceptable to kill animals, which involves some level of cruelty. It is not, except in war, socially acceptable to do that to humans (although we concoct all kinds of excuses for special circumstances).
Yes, but its not socially acceptable or lawful to be excessively cruel and torture them. Animals aren't people, and most people don't think they are. However they are alive, they do feel pain, and they do deserve to be treated with some level of kindness and respect.
For better or worse, that seems to depend entirely on the animal in question. Nobody laments the treatment of sea-sponges, the fact that they are animals instead of plants is basically just a curiosity of biology as far the majority is concerned when considering the ethics of them. Moving up from there: few (though probably more than in the case of sponges) worry about how we treat insects. We kill them with industrial grade chemicals (this concerns people, though not for reasons that are relevant), electricity, lasers, etc. There is little thought put into determining how to kill them ethically. Continuing on, rodents, snakes, and other medium sized pests: I would say that probably most people don't care how these are killed. Glue traps are very popular for instance, even though they are very cruel. These are the animals that we really start to see people caring in numbers worth paying attention to; humane killing devices and even live-capture traps are becoming increasingly popular for these sorts of animals.
Once you get larger than rats and snakes it seems most of the general public becomes fairly concerned about how the animals are killed. We have laws about what sort of traps trappers of small animals are supposed to use, and even most trappers are very serious about the ethics of what they are doing (for instance, they are typically very strict about how often they check their lines, so that animals are never trapped for excessively long periods of time.) As you get bigger and cuter more and more people start to care.
Of course all of this is basically just my observations of American cultures. The knobs on these different value settings are turned one way or the other for other cultures (in particular I think you can probably point to examples of both extreme settings of these values in various Asian cultures).
Anyway, as I said in another comment, my take on it is that we are all performing the same mental calculus (Americans, Vietnamese, French; Vegan Americans, Omnivore French, ... Everyone.) but we are going into the calculation with different values. Some Asian cultures have the "willingness to eat it" cranked way up so that they are more willing to eat animals that could be considered cute (sparrows, dogs, etc), while at the same time other Asian cultures have "willingness to eat it" cranked way down. The calculation is the same, only the values and weights assigned to things differ.
If you started to dial down the "willingness to eat it" I suspect that "creepy things" (snakes, bugs) might be the first to be spared, followed closely by whatever things that culture finds cute. Maybe the other way around.
Anyways, I wasn't talking about eating animals - I was talking about being cruel to animals. That's where the perceived consciousness plays a role - you don't want to hurt something that you see as more or less similar to you and capable of the same thoughts and emotions like you.
P.S. The fact that I'm talking like these are all facts and statistically proven theories is just for style. In reality I'm talking out of my a$$.