Despite the added fee, the unlimited plan will resonate with a distinct group of users, particularly gamers and online video addicts. Gamers require a broadband connection to handle the latency-sensitive nature of real-time sessions.

"The unlimited data plan is likely for the uber-data users that far exceed their data allowance each month," said Brett Sappington, director of research for Parks Associates, in a research note. 

From the article "AT&T Counters Cable Threat With Unlimited Broadband, But For Subscribers It Comes At A Cost" by Sean Buckley.