May as well chime in because I've wondered what's wrong with this myself...

My feeling is it's hard to think outside the box. Obviously: Creative Thinkers in short supply.

It is ridiculous to me how many movies show Humans as the winners against insurmountable odds. If there were other intelligent life out there and mankind was facing up against them, I really think man would loose and racism would be a big factor as to why.
Because of the inability to trust one another (or be trustworthy) humans have created a segregated planet. Even faced with a massive assault I doubt everyone would share what they know. As result they would be fighting with one hand behind their back if facing a united force. I'll leave this thought here for now because I don't really want to get into a social debate about what's wrong with humanity. At least it's not all bad...

Man is very warlike, hence, he's the one most likely to start a scuffle. He also is the top of the food chain as we know it and his inventiveness is amazing. It's hard to think of something more awesome than him. He breeds quickly, far more quickly than the definitions of other fantasy races. If you think about a long lived race it's easy to see how a spastic quick moving resourceful race would upset the scheme of things. If you lived forever you would probably put a lot more time into thinking about how you would do something instead of just doing it. For instance, these houses we have that are built to last 60 years or so...are you serious? Do you really want to be rebuilding your house all the time? I doubt it. You would probably figure out a way to do it right the first time so you didn't have to mess with it for at least 500 years. Thus, this kind of thinking would slow down how quickly you did things. I think this adds to the idea of man winning over Elves, etc. Man doesn't worry much about pollution if there is a profit to be made. There has to be laws or he just goes full steam ahead. He doesn't think a lot about the future issues of his actions. (Think about it next time you buy something like roofing shingles for you house....how many years warranty are you interested in? I bet you don't bother with that pricey lifetime one do you?) People don't even drive their cars until they are dust, they buy a new one as soon as they can. Hence, man is pretty short sighted and destructive. It works for him because he only lives to be 80 or so years old.

It's human thinking to believe we can overcome anything...At least it's an American idea from what I've learned from folks I've met around the world. And lets face it, for better or worse, Hollywood is in America.

I probably had more to say about this when I started but see the Ps. message. :-/

Ps. if this seems whacked in anyway I was interrupted several times while attempting to write it so my train of thought was all jumbled up.