I do believe that the industry and the people in it go too far with cosmetic surgery. It's not that it's always bad or it's always done wrong. Sometimes if done right it can turn out well, but too often that's not the case.
I think there are a couple of reasons for it being so prevalent. One is that there is a small amount of people that like the overboard surgery look or they will be the ones that hang out at the strip clubs all the time, but they also pay a lot more than an average person does for adult stuff so some people in the industry bend to what they want, even if the general public is anywhere from indifferent to seeing it as repulsive. They often hear from them more or those people will have more access and screw their view.
Another one is that there is too often a disconnect between the people in the industry and the rest of the public, even with people like here that are moderate fans of adult stuff. You couldn't even count the number of people here and elsewhere that people either mention they like natural breast, that they don't like implants, or it doesn't matter to them. Yet, there are still a lot of performers that think we always want them to have bigger breast for some reason.
A lot of people in porn are in a sub-culture of their own where they hang out with the same relatively small group of people and interact with them. It's sad, but a lot of those people are just plain idiots. A lot of them are scumbags. A lot of them are idiots and scumbags. When your surrounded by idiots all the time a lot of idiotic ideas have a chance of getting in your head.
Also, a lot of the fans of adult entertainment are fickle, impulsive, easily wowed by some new thing, and have the attention span of a six year old. A lot of them will just move on to the next thing after they tire with a performer, which sometimes doesn't take that long. It's pretty sad but something like breast implants can become a gimmick that will keep their attention a little while longer and extend a performers fifteen minutes of fame to the sixteenth minute. A performer's well being is often not even thought about much of the time by the people who watch their work.
A lot of porn performers aren't the most mentally stable or well grounded individuals in the world. Not that all of them have problems, because there are some that have a good head on their shoulders, but I would say enough of them are like that to be well above what a sampling of the same number of average people would be like. A lot of them have self image issues, and working in an industry that focus heavily on what they look like only magnifies it.
Finally some performers see it as a way of staving off aging, usually with little to no success in my opinion. Often it's plainly visible and a lot of the time makes it look worse. Some of them try to go back to the look they had when they were twenty years old when it's just not reasonable. It's often during this period you will see performers screwing with things other than their breast. It's sad because often the ones that do it don't realize they were pretty attractive, maybe even more than before, and that they can do almost nothing but mess with that.