MarketWatch: 'The popularity of early admissions plans is usually a surprise to Boomer and Gen X parents who attended college when maybe 10% to 15% of incoming classes came in via early decision, and they were usually the academic crème de la crème, says Robert Franek, editor-in-chief of The Princeton Review ... However, he notes that it is not unusual, certainly for Ivy League and many, many competitive schools across the country, to admit a significant percentage of their class early decision or early action, 30%, 35%, 40% or more.”
"Colleges love these plans because they make it easier for admissions offices to fill classrooms and dorms with paying customers. They also boost colleges’ all-important 'yield metric'—the percentage of admitted students who agree to matriculate ... That may be why colleges have added Early Decision 2, which follows the first round. Students who didn’t get into their favorite college under ED1 can apply to their second-choice school in ED2, which has a deadline in January."
"Traditionally students who applied for early decision came from wealthier families, because the colleges made their financial aid determinations when they sent out regular admissions acceptances and those who got in early were stuck with what the schools offered. Now, said Franek, colleges accept financial aid applications as early as October, which means that when students get early acceptances some time in December, they get their financial aid packages as well."