From what I've been told, NFL cheerleaders aren't actually paid very well and usually have to work another regular job type job job as you can't make a living being a NFL cheerleader.
Something to consider is that high school and college cheerleaders are in environments where usually their primary focus is supposed to be on school, not trying to scratch out a living. I question whether NFL cheerleaders could put in the time/training commitment that a high schooler or a college student could.
If it's any consolation, I've also read many teams in the NFL have discussed getting rid of female cheerleaders altogether. While they aren't paid much, they are an added expense for travel, facilities, accommodations, etc. Also you have very young attractive women who are generally not making a lot of money near rich, often married, giant sized alpha male athletes who are used to getting what they want when they want it.
Basically the situation is ripe for a scandal/financial blow to the franchise waiting to happen. Every cheerleader in the NFL is a walking lawsuit in my book. Most teams apparently have rules against cheerleaders dating players and vice versa for that reason.
The NFL has a symposium for drafted rookies each year, because they want to curb scandal. Topics include taking your used condoms with you and don't let a girl headbutt your fist. And don't screw the cheerleaders. I think the shift to competitive performances in cheerleading stems from the pervasive feminism in the western culture. It's not that they don't want you to objectify them at all, but only to do it in the way and manner that they deem appropriate. It's all a status grab in my book. But if you can do well enough to pay for college, then good for you. Too bad men in cheerleading are often excluded from scholarship potential. ( One of the few double standards I tend to agree with. )
I think the major differences are this
1) In college and high school, you can be ugly and still be a cheerleader and compete. At the NFL level, there are probably physical baselines. In places like Dallas and Miami, I think the bar is pretty high.
2) Most women basically hate each other. They are competitive. Especially in that 15-25 bracket where most of these cheerleaders probably reside. Especially when they line up similar in status. It's one thing to be the pretty girl surrounded by 20 plain girls. It's another thing to be a pretty girl and be around 19 other girls that guys think are even prettier than you and have it happen for the first time in your life. Anything they can do to tier out or draw lines between each other, even in a similar activity, is just another way to move oneself up and push someone else down in their eyes.
Maybe your girlfriend doesn't like how you might look at NFL cheerleaders, I don't know. She probably just wants you to agree with her, no matter what you actually feel.
Gekko
Boyfriend + 1 Girlfriend LOSER! 
