Reasons to not like mustangs:
smutts - not pure bred
can't register them for showing
I'm sure I will have more later, but thats a start
I have a lot I could say on this!!! BUT....As with any animal they will behave according to your behavior (ugly, dumb, and probably not pure bred)
I own a SSH, TWH, 2QH, A "smutt" as you put it, and a MUSTANG (breed of horse that was here long before most of your "show horses")
I would go with you are a person who totally pampers their horse for what kind of money they can make you (do you do with your children too?)
I am aware that not every horse person treats their horse as part of their family. And that is fine
I love the way my mustang is more independent than my other horses, it is only one of his most endearing qualities. I love the insight and years of knowledge I see when I look into his eyes. I also love the fact that when my children are around is the only time he wants the added attention that most domestic breeds of horses thrive on. He (Reno btw) is one of my best friends in the whole world!
Now that I vented on your hatred for a great animal! There are some bad ones that will never amount to anything, but there again that is the same with any horse, animal, even persons. Maybe you just need to try and see them for what they are another breed of big beautiful amazing animal like any other!