My alma mater is pretty small, and my chapter has 46 girls currently in their pledge class. They were the only sorority on campus to make quota this year too, but that doesn't mean that they did anything wrong or that their members are snobby. It simply means that a lot of girls were impressed by them during Rush and wanted to go DZ.
The sorority you're referring to may have simply had a really phenomenal rush this year. A large pledge class means that the Greek system is doing well at your campus, and that's definitely something to be proud of -- not something to be upset about.
***25 isn't a ridiculously large size for a pledge class on any campus -- the girls that I help advise at UGA have upwards of 55 new members in their pledge classes and I know of other DZ chapters who have classes with 70 or more.***