Note: I'm not married, nor am I at the age where a ton of my friends are getting married.
I might guess that another root cause for the Bridezilla phenomenon is that women are expecting a huge, lavish wedding and expecting to be the center of attention and expecting everything to go perfectly. However, events like this rarely go perfectly.
I know from personal experience in non-wedding situations, the times when I get most disappointed and angry and even "psycho bitch" status is when I am expecting something and it doesn't happen. Little things like expecting to go to the beach on your one day off and instead the day gets wasted by things beyond your control. I realize that the anger is a byproduct of disappointment, however it doesn't change the anger in the moment.
Also, weddings are extremely stressful periods of time and I find that stress doesn't help you manage or deal with your emotions properly. Instead of clearly expressing what you want/need in a way that others can understand and help you, you snap at people. When I'm stressed I feel like "I don't have the time to deal with this, just fucking do it" rather than taking a moment to calmly express what needs to happen.
These two things combined are never good and probably contribute more to the bridezilla than "women are ignored except on their wedding day."